T3 Uptake Test (THBR)

A T3 test helps to determine whether the thyroid is functioning properly. It is ordered primarily to help diagnose hyperthyroidism and may be ordered to help monitor the progress of a patient with a known thyroid disorder. The T3 test is usually ordered following an abnormal TSH and T4 test. Either the total T3 or the free T3 may be ordered. Since most of the T3 is bound to protein, the total T3 can be affected by protein levels and protein binding ability, but the free T3 is not. T3 testing may be ordered along with thyroid antibodies to help diagnose Graves’ disease, an autoimmune disorder that is the most common cause of hyperthyroidism.

When is a T3 Uptake test ordered? 
A total or free T3 test may be ordered when a patient has an abnormal TSH and/or T4 test result. It may be ordered as part of the investigative workup when a patient has symptoms suggesting hyperthyroidism. One of the T3 tests may sometimes be ordered at intervals to monitor a known thyroid condition and to help monitor the effectiveness of treatment for hyperthyroidism.

What does the T3 Uptake test result mean? 
NOTE: This test has no single number that identifies an abnormal result. Your lab report (see a sample report) should include a range of numbers (reference range) that identifies what is expected for you based on your age, sex, and the method used in that laboratory. You can find more information about expected results at Reference Ranges and What They Mean. Lab Tests Online strongly recommends that you discuss the meaning of your test results with your doctor.

Increased or decreased thyroid hormone results indicate that there is an imbalance between the body’s requirements and supply, but they do not tell the doctor specifically what is causing the excess or deficiency. The following table summarizes test results and their potential meaning.

TSH	T4	T3	Interpretation
High	Normal	Normal	Mild (subclinical) hypothyroidism
High	Low	Low or normal	Hypothyroidism
Low	Normal	Normal	Mild (subclinical) hyperthyroidism
Low	High or normal	High or normal	Hyperthyroidism
Low	Low or normal	Low or normal	Nonthyroidal illness; Rare pituitary (secondary) hypothyroidism

If a patient is being treated with anti-thyroid medication for hyperthyroidism and the T3 (or more frequently, the T4 or TSH) is normal, then it is likely that the medication is controlling the condition. If the T3 (or T4) is elevated, then the medication is not sufficient to control the condition and the patient may be experiencing symptoms associated with hyperthyroidism.

Is there anything else I should know? 
Many medications—including estrogen, certain types of birth control pills, and large doses of aspirin—can affect total T3 test results, so tell your doctor about any drugs you are taking. In general, free T3 levels are not affected by these medications.

When you are sick, your body decreases production of T3 from T4. Most people who are sick enough to be in the hospital will have a low T3 or free T3 level. For this reason, doctors do not usually use T3 as a routine thyroid test for patients in hospitals.

Thyroid-stimulating hormone Test (TSH)

The TSH test is often the test of choice for evaluating thyroid function and/or symptoms of hyper- or hypothyroidism. It is frequently ordered along with or preceding a T4 test. Other thyroid tests that may be ordered include a T3 test and thyroid antibodies (if autoimmune-related thyroid disease is suspected).  

TSH testing is used to:


When is a TSH test ordered? 
The doctor may order a TSH test when a patient has symptoms of hyper- or hypothyroidism and/or when a patient has an enlarged thyroid gland. It may be ordered at regular intervals to monitor the effectiveness of treatment when a patient is being treated for a known thyroid disorder.

TSH screening is routinely performed in the United States on newborns as part of each state’s newborn screening program. The American Thyroid Association recommends that adults older than age 35 be screened for thyroid disease with a TSH test every five years, although other organizations, such as the U.S. Preventive Services Task Force, challenge this recommendation. Several organizations recommend instead screening women over 50 or those at high risk for thyroid disorders, such as pregnant and postpartum women.

What does the TSH test result mean? 
NOTE: This test has no single number that identifies an abnormal result. Your lab report (see a sample report) should include a range of numbers (reference range) that identifies what is expected for you based on your age, sex, and the method used in that laboratory. You can find more information about expected results at Reference Ranges and What They Mean. Lab Tests Online strongly recommends that you discuss the meaning of your test results with your doctor.

A high TSH result often means an underactive thyroid gland that is not responding adequately to the stimulation of TSH due to some type of acute or chronic thyroid dysfunction. Rarely, a high TSH result can indicate a problem with the pituitary gland, such as a tumor producing unregulated levels of TSH. A high TSH value can also occur when patients with a known thyroid disorder (or those who have had their thyroid gland removed) are receiving too little thyroid hormone medication.

A low TSH result can indicate an overactive thyroid gland (hyperthyroidism) or excessive amounts of thyroid hormone medication in those who are being treated for an underactive (or removed) thyroid gland. Rarely, a low TSH result may indicate damage to the pituitary gland that prevents it from producing adequate amounts of TSH.

Whether high or low, an abnormal TSH indicates an excess or deficiency in the amount of thyroid hormone available to the body, but it does not indicate the reason why. An abnormal TSH test result is usually followed by additional testing to investigate the cause of the increase or decrease.

The following table summarizes test results and their potential meaning:

TSH	T4	T3	Interpretation
High	Normal	Normal	Mild (subclinical) hypothyroidism
High	Low	Low or normal	Hypothyroidism
Low	Normal	Normal	Mild (subclinical) hyperthyroidism
Low	High or normal	High or normal	Hyperthyroidism
Low	Low or normal	Low or normal	Nonthyroidal illness; Rare pituitary (secondary) hypothyroidism

Is there anything else I should know? 
Many medications — including aspirin and thyroid-hormone replacement therapy — may affect thyroid gland function test results, so tell your doctor about any drugs you are taking.

When your doctor adjusts your dose of thyroid hormone, it is important to wait at least one to two months before checking your TSH again so that your new dose can have its full effect.

Extreme stress and acute illness may also affect TSH test results, and results may be low during the first trimester of pregnancy.

Thyroxine Test (T4)

Total T4 and free T4 are two separate tests that can help the doctor evaluate thyroid function. The total T4 test has been used for many years to help diagnose hyper- and hypothyroidism. It is a useful test but can be affected by the amount of protein available in the blood to bind to the hormone. The free T4 test is a newer test that is not affected by protein levels. Since free T4 is the active form of thyroxine, it is thought by many to be a more accurate reflection of thyroid hormone function and, in most cases, its use has replaced that of the total T4. Whichever thyroxine measurement is ordered, it is usually ordered along with or following a TSH test. This helps the doctor to determine whether the thyroid hormone feedback system is functioning as it should, and the results of the tests help to distinguish between different causes of hyper- and hypothyroidism. Sometimes a T3 test will also be ordered to give the doctor additional diagnostic information.

A T4 and TSH test may be ordered to help evaluate a patient with a goiter and to aid in the diagnosis of female infertility. If the doctor suspects that the patient may have an autoimmune-related thyroid condition, thyroid antibodies may be ordered along with a T4. In patients with known thyroid dysfunction, T4 and/or TSH tests may be ordered to monitor thyroid function.

In the United States, newborns are commonly screened for T4 levels as well as TSH concentrations to check for congenital hypothyroidism, which can cause mental retardation if left untreated.  

When is a T4 test ordered? 
A total T4 or free T4 test is primarily ordered in response to an abnormal TSH test result. Sometimes the T4 will be ordered along with a TSH to give the doctor a more complete evaluation of the adequacy of the thyroid hormone feedback system. These tests are usually ordered when a patient has symptoms of hyper- or hypothyroidism. Sometimes they are ordered as screening tests during routine blood testing, but expert opinions vary on who can benefit from screening and at what age to begin. In patients with known thyroid disorders, the TSH and sometimes T4 are ordered at intervals to monitor the effectiveness of treatment. In pregnant women with thyroid disorders, the doctor is likely to order thyroid testing early and late in the pregnancy and for a time period following delivery to monitor the mother and baby. Thyroid hormone screening is commonly performed on newborns in the United States as part of newborn screening programs.

What does the T4 test result mean? 
NOTE: This test has no single number that identifies an abnormal result. Your lab report (see a sample report) should include a range of numbers (reference range) that identifies what is expected for you based on your age, sex, and the method used in that laboratory. You can find more information about expected results at Reference Ranges and What They Mean. Lab Tests Online strongly recommends that you discuss the meaning of your test results with your doctor.

In general, high free or total T4 results may indicate an overactive thyroid gland (hyperthyroidism), and low free or total T4 results may indicate an underactive thyroid gland (hypothyroidism). The test results alone are not diagnostic but will prompt the doctor to perform additional testing to investigate the cause of the excess or deficiency. Both decreased and increased T4 results are associated with a variety of temporary and chronic thyroid conditions. Low T4 results in conjunction with a low TSH level or high T4 results along with a high TSH may indicate a pituitary gland condition.

The following table summarizes test results and their potential meaning:

TSH	T4	T3	Interpretation
High	Normal	Normal	Mild (subclinical) hypothyroidism
High	Low	Low or normal	Hypothyroidism
Low	Normal	Normal	Mild (subclinical) hyperthyroidism
Low	High or normal	High or normal	Hyperthyroidism
Low	Low or normal	Low or normal	Nonthyroidal illness; Rare pituitary (secondary) hypothyroidism

Is there anything else I should know? 
Many medications—including estrogen, certain types of birth control pills, and large doses of aspirin—can affect total T4 test results, so tell your doctor about any drugs you are taking. In general, free T4 levels are not affected by these medications.

Insulin-like Growth Factor 1 Test (IGF-1)

IGF-1 is measured to help diagnose the cause of growth abnormalities and to evaluate pituitary function. It is not diagnostic of GH deficiency but may be ordered along with GH stimulation tests to offer additional information. IGF-1 levels and the measurement of GH can also provide information related to GH insensitivity.

IGF-1 may be ordered with other pituitary hormone tests, such as adrenocorticotropic hormone (ACTH), to help diagnose hypopituitarism. It may be used to monitor the effectiveness of treatment for growth hormone deficiencies and growth hormone insensitivity.

IGF-1 testing and a GH suppression test can be used to detect a GH-producing pituitary tumor. Its presence is then confirmed with imaging scans that help identify and locate the tumor. If surgery is necessary, GH and IGF-1 levels are measured after the tumor’s removal to determine whether or not all of it was successfully removed. Drug and/or radiation therapy may be used in addition to (or sometimes instead of) surgery to try to decrease GH production and return IGF-1 to normal or near normal concentrations. IGF-1 may be used to monitor the effectiveness of this therapy at regular intervals for years afterward to monitor GH production and to detect tumor recurrence.

When is a GF-1 test ordered? 
IGF-1 testing may be ordered, along with a GH stimulation test, when a child has symptoms of GH deficiency, such as a slowed growth rate and short stature. They also may be ordered when adults have symptoms that the doctor suspects may be due to a GH deficiency. An IGF-1 also may be ordered when a doctor suspects that a person has an underactive pituitary gland and at intervals to monitor patients on GH therapy.

IGF-1 testing may be ordered, along with a GH suppression test, when a child has symptoms of gigantism, an adult shows signs of acromegaly, and/or when a doctor suspects that a patient has hyperpituitarism.

When a GH-producing pituitary tumor is found, GH and IGF-1 are ordered after the tumor is surgically removed to determine whether all of the tumor has been extracted. IGF-1 also is ordered at regular intervals when a patient is undergoing the drug and/or radiation therapy that frequently follow tumor surgery.

IGF-1 levels may be ordered at regular intervals for many years to monitor a patient’s GH production and to watch for pituitary tumor recurrence.

What does the GF-1 test result mean? 
NOTE: This test has no single number that identifies an abnormal result. Your lab report (see a sample report) should include a range of numbers (reference range) that identifies what is expected for you based on your age, sex, and the method used in that laboratory. You can find more information about expected results at Reference Ranges and What They Mean. Lab Tests Online strongly recommends that you discuss the meaning of your test results with your doctor.

Normal concentrations of IGF-1 must be considered in context. Some patients can have a GH deficiency and still have a normal IGF-1 concentration.

Decreased IGF-1
If IGF-1 concentrations are decreased, then it is likely that there is a deficiency of GH (GH Deficiency; GHD) or an insensitivity to GH. If this is in a child, the GH deficiency may have already caused short stature and delayed development and may be treated with GH supplementation. Adults will have an age-related decrease in production, but lower than expected concentrations may reflect a GH deficiency or insensitivity.

If a decrease in IGF-1 is due to a more general decrease in pituitary function (hypopituitarism), then several of the patient’s pituitary hormones will need to be evaluated and may be supplemented to bring them up to normal levels. Reduced pituitary function may be due to inherited defects or can rise as a result of pituitary damage following conditions such as trauma, infections, and inflammation.

Decreased levels of IGF-1 also may be seen with nutritional deficiencies (including anorexia nervosa), chronic kidney or liver disease, inactive/ineffective forms of GH, and with high doses of estrogen.

Increased IGF-1
Elevated levels of IGF-1 usually indicate an increased production of GH. Since GH levels vary throughout the day, IGF-1 concentrations are a reflection of average GH production, not of the actual amount of GH in the blood. This is accurate up to the point at which the liver’s capacity to produce IGF-1 is reached. With severely increased GH production, IGF-1 levels will stabilize at an elevated maximum concentration.

Increased concentrations of GH and IGF-1 are normal during puberty and pregnancy but otherwise are most frequently due to pituitary tumors (usually benign). If other pituitary hormones are also abnormal, then the patient may have a condition causing general hyperpituitarism.

If IGF-1 is still elevated after the surgical removal of a pituitary tumor, then the surgery may not have been fully effective. Decreasing IGF-1 concentrations during subsequent drug and/or radiation therapies indicate that the treatment is lowering GH production. If levels of IGF-1 become “normalized,” then the patient is no longer producing excess amounts of GH. When a patient is undergoing long term monitoring, an increase in IGF-1 levels may indicate a recurrence of the pituitary tumor.

Is there anything else I should know? 
If an IGF-1 level is normal and the doctor still strongly suspects a GH deficiency, then he may order another test, an IGF BP 2 or IGF BP 3 (insulin-like growth factor binding protein 2 or 3), to help confirm the GH deficiency.

Testosterone Testing

Testosterone testing is used to diagnose several conditions in men, women, and boys. These conditions include:



When is Testosterone testing ordered? 
In boys, the test is ordered, often along with the FSH and LH tests, if puberty is delayed or slow in developing. Although there are differences from individual to individual as to when puberty begins, generally by the age of 10 years, there are hormonal and physical manifestations of the onset of puberty. A delay can occur if the testes do not produce enough testosterone or if the pituitary does not produce enough LH.

The test also can be ordered if a young boy seems to be undergoing a very early (precocious) puberty with obvious secondary sex characteristics, such as an enlarged penis, development of muscle mass, and growth of body hair. Causes of precocious puberty in boys, due to increased testosterone, include various tumors and congenital adrenal hyperplasia.

In men, the test may be ordered when infertility is suspected or if the patient has a decreased sex drive or erectile dysfunction, all of which can result from low testosterone levels.

In women, testosterone testing may be done if a patient has irregular or no menstrual periods, is having difficulty getting pregnant, or appears to have masculine features, such as facial and body hair, male pattern baldness, and a low voice. Testosterone levels can rise because of tumors that develop in either the ovary or adrenal gland or because of other conditions, such as polycystic ovarian syndrome (PCOS).

What does the Testosterone test result mean? 
NOTE: This test has no single number that identifies an abnormal result. Your lab report (see a sample report) should include a range of numbers (reference range) that identifies what is expected for you based on your age, sex, and the method used in that laboratory. You can find more information about expected results at Reference Ranges and What They Mean. Lab Tests Online strongly recommends that you discuss the meaning of your test results with your doctor.

There is great variability in testosterone levels between men and a broad range in age-related values for testosterone. It is normal for testosterone levels to decline as men age.

However, in males, a decreased testosterone level may indicate hypothalamic or pituitary disease or damage to the testes. Genetic diseases also can cause decreased testosterone production in young men (Klinefelter’s, Kallman’s, and Prader-Willi syndromes) or testicular failure and infertility (as in myotonic dystrophy, a form of muscular dystrophy). A decreased testosterone level also can indicate impaired testosterone production because of acquired damage to the testes, such as alcoholism, physical injury, or viral diseases like mumps.

Increased testosterone levels in males can indicate testicular tumors , adrenal tumors that are producing testosterone, or use of androgens (also called anabolic steroids). Increased testosterone in boys is usually the cause of early puberty.

In women, increased testosterone levels can indicate PCOS or an ovarian or adrenal gland tumor.

Is there anything else I should know? 
Alcoholism and liver disease in males can decrease testosterone levels. Drugs, including androgens and steroids, can also decrease testosterone levels. Prostate cancer responds to androgens, so many men with advanced prostate cancer receive drugs that lower testosterone levels.

Women taking estrogen therapy may have increased testosterone levels. Anticonvulsants, barbiturates, and clomiphene can cause testosterone levels to rise.

Follicle-stimulating Hormone Test (FSH)

FSH is often used in conjunction with other tests (LH, testosterone, estradiol, and progesterone) in the workup of infertility in both men and women. FSH levels are used to help determine the reason a man has a low sperm count. FSH levels are also useful in the investigation of menstrual irregularities and to aid in the diagnosis of pituitary disorders or diseases involving the ovaries or testes. In children, FSH and LH are used to diagnose delayed or precocious (early) puberty.

When is the FSH ordered? 
In women and men, FSH and LH are ordered as part of the workup of infertility and pituitary or gonadal disorders. FSH may be ordered to determine if a woman has reached menopause. In children, FSH and LH may be ordered when a boy or girl does not appear to be entering puberty at an appropriate age (either too late or too soon). Signs of puberty may include:



If any or some of these signs appear at a younger than average age or are delayed beyond the expected age range for puberty, it may be an indication of a more serious problem involving the hypothalamus, pituitary, gonads (ovaries or testes) or other systems. The measurement of LH and FSH may differentiate between benign symptoms and true disease. Once it is established that symptoms are a result of true disease, further testing can be done to discern the underlying cause.

What does the FSH test result mean? 
NOTE: This test has no single number that identifies an abnormal result. Your lab report (see a sample report) should include a range of numbers (reference range) that identifies what is expected for you based on your age, sex, and the method used in that laboratory. You can find more information about expected results at Reference Ranges and What They Mean. Lab Tests Online strongly recommends that you discuss the meaning of your test results with your doctor.

In women, FSH and LH levels can help to differentiate between primary ovarian failure (failure of the ovaries themselves) and secondary ovarian failure (failure of the ovaries due to disorders of either the pituitary or the hypothalamus). Increased levels of FSH and LH are consistent with primary ovarian failure. Some causes of primary ovarian failure are listed below.

Developmental defects:


Premature ovarian failure due to:


Chronic anovulation (failure to ovulate) due to:


When a woman enters menopause and her ovaries stop working, FSH levels will rise.

Low levels of FSH and LH are consistent with secondary ovarian failure due to a pituitary or hypothalamic problem.

In men, high FSH levels are due to primary testicular failure. This can be due to developmental defects in testicular growth or to testicular injury, as indicated below.

Developmental defects:


Testicular failure:


Low levels are consistent with pituitary or hypothalamic disorders.

In young children, high levels of FSH and LH and/or development of secondary sexual characteristics at an unusually young age are an indication of precocious puberty. This is much more common in girls than in boys. This premature development can have many different underlying causes that need to be diagnosed and treated. Some of the causes include:


Normal prepubescent levels of LH and FSH in children exhibiting some signs of pubertal changes may indicate a benign form of precocious puberty with no underlying or discernable cause or may just be a normal variation of puberty.

In delayed puberty, LH and FSH levels can be normal or below what is expected for a youth within the age range of puberty. The test for LH response to GnRH may need to be performed along with other testing to diagnose the reason for the delayed puberty. Some of the causes for delayed puberty can include:


Is there anything else I should know? 
FSH results can be increased with use of cimetidine, clomiphene, digitalis, and levodopa. FSH results can decrease with oral contraceptives, phenothiazines, and hormone treatments.

If you’ve recently had a nuclear medicine scan, the radioisotopes used in the scan may interfere with results of the FSH test.

Luteinizing Hormone Test (LH)

LH is often used in conjunction with other tests (FSH, testosterone, estradiol and progesterone) in the workup of infertility in both men and women. LH levels are also useful in the investigation of menstrual irregularities and to aid in the diagnosis of pituitary disorders or diseases involving the ovaries or testes.

A urine test may be used to detect the surge in LH that indicates that ovulation will occur in the next 1-2 days.

In children, FSH and LH are used to diagnose delayed and precocious (early) puberty.

LH is sometimes measured in relation to gonadotropin releasing hormone (GnRH) to distinguish between primary or secondary disorder of the hypothalamic-pituitary axis. GnRH is the hormone produced by the hypothalamus that stimulates the pituitary to release LH and FSH. For this test, a baseline blood sample is drawn and then the patient is given an injection of GnRH. Subsequent blood samples are drawn at specified times, and the level of LH is measured. This test can help differentiate between disease of the ovaries or testes (primary) and a disorder of the pituitary or hypothalamus (secondary). It is also often helpful in the evaluation of precocious or delayed puberty.

When is a Luteinizing test ordered? 
In women and men, LH (along with FSH) is ordered as part of the workup of infertility and pituitary or gonadal disorders.

The test may be ordered along with an FSH test if a women is having irregular menstrual periods to help determine if she has reached menopause. LH and FSH may be ordered when a boy or girl does not appear to be entering puberty at an appropriate age (either too late or too soon). Signs of puberty may include:



If any or some of these signs appear at a younger than average age or are delayed beyond the expected age range for puberty, it may be an indication of a more serious problem involving the hypothalamus, pituitary, gonads (ovaries or testes), or other systems. The measurement of LH and FSH may differentiate between benign symptoms and true disease. Once it is established that symptoms are a result of true disease, further testing can be done to discern the underlying cause.

What does the Luteinizing test result mean? 
NOTE: This test has no single number that identifies an abnormal result. Your lab report (see a sample report) should include a range of numbers (reference range) that identifies what is expected for you based on your age, sex, and the method used in that laboratory. You can find more information about expected results at Reference Ranges and What They Mean. Lab Tests Online strongly recommends that you discuss the meaning of your test results with your doctor.

In women, LH and FSH levels can help to differentiate between primary ovarian failure (failure of the ovaries themselves or lack of ovarian development) and secondary ovarian failure (failure of the ovaries due to disorders of either the pituitary or the hypothalamus). Increased levels of LH and FSH are seen in primary ovarian failure. Some causes of primary ovarian failure are listed below.

Developmental defects:


Premature ovarian failure due to:


Chronic anovulation (failure to ovulate) due to:


When a woman enters menopause and her ovaries stop working, LH levels will rise.

Low levels of LH and FSH are seen in secondary ovarian failure and indicate a problem with the pituitary or hypothalamus.

In men, high LH levels indicate primary testicular failure. This can be due to developmental defects in testicular growth or to testicular injury, as described below.

Developmental defects:


Testicular failure:


Low levels are consistent with pituitary or hypothalamic disorders.

The results for the test for LH response to GnRH can help differentiate between primary dysfunction (failure of the ovaries or testes) and secondary disorder (a problem involving the pituitary or hypothalamus). Once the baseline level of LH has been measured, a dose of GnRH is given by injection. A subsequent increase in the level of LH indicates that the pituitary responded to the GnRH and points to a disorder involving the ovaries or testes. A reduced level of LH shows that the pituitary did not respond to the GnRH and suggests a disease involving the pituitary or hypothalamus.

In young children, high levels of LH and FSH and/or development of secondary sexual characteristics at an unusually young age are an indication of precocious puberty. This is much more common in girls than in boys. This premature development can have many different underlying causes that need to be diagnosed and treated. Some of the causes include:


ANormal prepubescent levels of LH and FSH in children exhibiting some signs of pubertal changes may indicate a benign form of precocious puberty with no underlying or discernable cause or may just be a normal variation of puberty.

In delayed puberty, LH and FSH levels can be normal or below what is expected for a youth within the age range of puberty. The test for LH response to GnRH may need to be performed along with other testing to diagnose the reason for the delayed puberty. Some of the causes for delayed puberty can include:


Is there anything else I should know? 
Some drugs can cause LH to increase, such as anticonvulsants, clomiphene, and naloxone, while others cause LH to decrease, such as digoxin, oral contraceptives, and hormone treatments.

If you’ve recently had a nuclear medicine scan, the radioisotopes used in the scan may interfere with results of the LH test.

Dehydroepiandrosterone (DHEA) Sulfate Test

DHEAS levels are not routinely measured. Unless you have symptoms that warrant its use, you will most likely never have a DHEAS test done. DHEAS, testosterone, and several other androgens are used to evaluate adrenal function and to distinguish androgen-secreting conditions that are caused by the adrenal glands from those that originate in the ovaries or testes. DHEAS can be measured to help diagnose adrenocortical tumors (tumors in the cortex of the adrenal gland), adrenal cancers, and adrenal hyperplasia (which may be congenital or adult onset) and to separate these conditions from ovarian tumors and cancers.

Concentrations of DHEAS are often measured, along with other hormones such as FSH, LH, prolactin, estrogen, and testosterone, to help diagnose polycystic ovarian syndrome (PCOS) and to help rule out other causes of infertility, amenorrhea, and hirsutism.

DHEAS levels may be ordered, along with other hormones, to investigate and diagnose the cause of virilization in young girls and precocious puberty in young boys.

When is a DHEA test ordered? 
A DHEAS test may be ordered, along with other hormone tests, whenever excess (or more rarely deficient) androgen production is suspected and/or when your doctor wants to evaluate your adrenal gland function.

It may be measured when a woman presents with symptoms such as: hirsutism, alopecia, amenorrhea, infertility, acne, increased muscularity, and decreased breast size. It may also be ordered when a young girl shows signs of virilization, such as hirsutism, a deep voice, or when a female infant has ambiguous genitalia wherein the clitoris is overgrown but the internal female organs usually appear normal.

DHEAS may also be measured when young boys show signs of precocious puberty, the development of a deeper voice, pubic hair, muscularity, and an enlarged penis well before the age of normal puberty.

What does the DHEA test result mean? 
NOTE: This test has no single number that identifies an abnormal result. Your lab report (see a sample report) should include a range of numbers (reference range) that identifies what is expected for you based on your age, sex, and the method used in that laboratory. You can find more information about expected results at Reference Ranges and What They Mean. Lab Tests Online strongly recommends that you discuss the meaning of your test results with your doctor.

Low levels of DHEAS may be due to adrenal dysfunction or hypopituitarism - a condition that causes decreased levels of the pituitary hormones that regulate the production and secretion of adrenal hormones. Normal DHEAS levels, along with other normal androgen levels, may indicate that the adrenal gland is functioning normally or (more rarely) that an adrenal tumor or cancer present is not secreting hormones. Normal levels of DHEAS may be seen with PCOS, as this disorder is usually related to ovarian androgen production (primarily testosterone).

Elevated levels of DHEAS may indicate an adrenocortical tumor, adrenal cancer, or adrenal hyperplasia. Increased levels of DHEAS are not diagnostic of a specific condition; they usually indicate the need for further testing to pinpoint the cause of the hormone imbalance.

Is there anything else I should know? 
DHEAS levels are normally high in both male and female newborns. They drop sharply shortly after birth, then rise again during puberty. DHEAS concentrations peak after puberty, and then, like other male and female hormones, the levels tend to decline with aging.

People taking DHEA supplements will have elevated blood levels of DHEAS.

Sex Hormone-binding Globulin (SHGB) Test

A SHBG test is primarily ordered to evaluate the status of a patient’s androgens - the male hormones. With men, the issue of concern is testosterone deficiency, while with women the concern is excess testosterone production. A total testosterone may be ordered prior to or along with a SHBG test.

SHBG and testosterone levels may be ordered on an adult male to help determine the cause of infertility, a decreased sex drive, and erectile dysfunction, especially when total testosterone results are inconsistent with clinical signs.

In women, small amounts of testosterone are produced by the ovaries and adrenal glands. Even slight increases in testosterone production can disrupt the balance of hormones and cause symptoms such as amenorrhea, infertility, acne, and hirsutism. These symptoms and others are often seen with polycystic ovarian syndrome, a condition characterized by an excess production of androgens. SHBG and testosterone testing may be useful in helping to detect and evaluate excess testosterone production and/or decreased SHBG concentrations.

For both sexes, a free testosterone, albumin level, and one or more other hormones, such as prolactin, estradiol, and LH (lutenizing hormone) may also be performed to evaluate a patient’s existing balance of hormones.

Sometimes, a total testosterone and SHBG are ordered to evaluate free androgens by calculating the Free Androgen Index (FAI). This equation gives doctors an idea of the quantity of testosterone that is not bound to SHBG and is calculated as follows: FAI=Total Testosterone / SHBG.

When is a SHGB test ordered? 
Currently, the SHBG test is not performed frequently or routinely. In many cases, doctors feel that the total testosterone, and perhaps free testosterone, provides sufficient information. SHBG is ordered primarily when the total testosterone results do not seem to be consistent with clinical signs, such as decreased sex drive in men or hirsutism in women.

What does the SHGB test result mean? 
NOTE: This test has no single number that identifies an abnormal result. Your lab report (see a sample report) should include a range of numbers (reference range) that identifies what is expected for you based on your age, sex, and the method used in that laboratory. You can find more information about expected results at Reference Ranges and What They Mean. Lab Tests Online strongly recommends that you discuss the meaning of your test results with your doctor.

When SHBG levels are increased beyond what is expected, there is likely to be less free testosterone available to the tissues than is indicated by the total testosterone. If SHBG concentrations are decreased, more of the total testosterone is “bioavailable” - not bound to SHBG.

Is there anything else I should know? 
SHBG concentrations are normally high in children of both sexes. After puberty, SHBG levels decrease more rapidly in males than in females. Levels are normally stable in adults and then begin to increase in the elderly male at the same time that total testosterone levels begin to decrease. In postmenopausal women, SHBG, testosterone, and estrogen concentrations decrease as hormone production by the ovaries tapers off.

Bioavailable testosterone is becoming an increasingly important concept to both doctors and researchers. It may be measured by removing the SHBG-bound testosterone from the collected blood sample and then analyzing what’s left. An estimate can also be calculated using the Free Androgen Index (see above).

Although SHBG is not usually ordered to diagnose or monitor these conditions, increases in SHBG are seen with liver disease, hyperthyroidism, anorexia, and estrogen use (hormone replacement therapy and oral contraceptives). Decreases in SHBG are seen with obesity, hypothyroidism, androgen use, and Cushing’s disease.

Prostate-specific Antigen Test (PSA)

The total PSA test and digital rectal exam (DRE) are ordered to screen both asymptomatic and symptomatic men for prostate cancer. Since the DRE can cause a temporary elevation in PSA, the blood is usually collected prior to performing the DRE. If either the PSA or the DRE are found to be abnormal, then the doctor may choose to follow this testing with a prostate biopsy and perhaps imaging tests, such as an ultrasound. If the DRE is normal but the PSA is moderately elevated, the doctor may order a free PSA test to look at the ratio of free to total PSA. This can help to distinguish between prostate cancer and other non-cancer causes of elevated PSA. Since the total PSA test can be elevated temporarily for a variety of reasons, a doctor may order another PSA a few weeks after the first to determine if the PSA is still elevated.

The cPSA is a relatively new test that may be ordered, along with the DRE, as an alternative to the total PSA. There is hope that this test could be more specific than the total PSA (better at detecting cancer-related PSA), but findings have been mixed and its ultimate clinical utility has yet to be established. The cPSA is an option that doctors can discuss with their patients. Its use may expand and/or be better defined as additional studies are conducted and findings are reported.

If prostate cancer is diagnosed, then the total PSA may be used as a monitoring tool to help determine the effectiveness of treatment. It may also be ordered at regular intervals after treatment to detect recurrence of the cancer.

In cases where the cancer appears to be slow-growing and the doctor and patient decide to monitor its progress rather than pursue immediate treatment (called “watchful waiting”), total PSA levels are ordered at frequent intervals to monitor the change in PSA over time.

When is a PSA test ordered? 
There is no consensus among the experts currently about when the PSA test should be ordered to screen asymptomatic males. Over-diagnosing, identifying cases of prostate cancer that may never cause significant health problems, must be balanced against missing the detection of aggressive cancers. There are national organizations, such as the National Cancer Institute and Centers for Disease Control and Prevention, that do not recommend routine screening at this time. Others, such as the American Cancer Society (ACS), recommend that doctors offer total PSA tests and DRE annually to all men, beginning at age 50 and to those at an increased risk of prostate cancer, such as American men of African descent and men with a family history of the disease, beginning at age 40 or 45. The ACS recommends that doctors discuss the testing options, benefits, and potential side effects with their male patients so that they can make informed choices. (See Prostate Cancer Screening for Adults and Adults 50 and Up.) The total PSA test and DRE may also be ordered when a patient has symptoms that could be due to prostate cancer, such as difficult, painful, and/or frequent urination, back pain, and/or pelvic pain. Since these symptoms are seen with a variety of other conditions, including infection and prostatitis, the doctor will also frequently order other tests, such as a urine culture. Some of these conditions can themselves cause temporary increases in PSA levels. If a total PSA level is elevated, a doctor may order a repeat test a few weeks later to determine whether the PSA concentrations have returned to normal.

A free PSA is primarily ordered when a patient has a moderately elevated total PSA that does not appear to be caused by a non-cancer-related condition. The results give the doctor additional information about whether a patient is at an increased risk of having prostate cancer and help with the decision of whether to biopsy the prostate.

The total PSA may be ordered during treatment of patients who have been diagnosed with prostate cancer to verify the effectiveness of treatment and at regular intervals after treatment to monitor for cancer recurrence. It is also ordered at regular intervals when a patient with cancer is participating in “watchful waiting” and not currently treating their prostate cancer.

What does the PSA test result mean? 
The normal value for total PSA has been set at less than 4.0 ng/ml (nanograms per milliliter of blood). There are some that feel that this level should be lowered to 2.5 ng/ml in order to detect more cases of prostate cancer. Others argue that this would exacerbate over-diagnosing and over-treating cancers that are not clinically significant.

There is agreement that patients with a total PSA level greater than 10.0 ng/ml are at an increased risk for prostate cancer (more than a 67% chance, according to the ACS). Levels between 4.0 ng/ml and 10.0 ng/ml may indicate prostate cancer (about a 25% chance, according to the ACS), BPH, or prostatitis. These conditions are more common in the elderly, as is a general increase in PSA levels. Concentrations of total PSA between 4.0 ng/ml and 10.0 ng/ml are often referred to as the “gray zone.” It is in this range that the free PSA is the most useful. When patients in the gray zone have decreased levels of free PSA, they have a higher probability of prostate cancer; when they have elevated levels of free PSA, the risk is diminished. The ratio of free to total PSA can help the doctor decide whether or not a prostate biopsy should be performed.

When the cPSA test is used as a screening tool, increased levels may indicate an increased risk of prostate cancer, while lower levels indicate a decreased risk.

In addition to the introduction of the free PSA and cPSA tests, there have been efforts to increase the usefulness of the total PSA as a screening tool. While none of these efforts have been widely accepted yet, researchers are studying them and some doctors are utilizing them. They include:


During treatment for prostate cancer, the PSA level should begin to fall. At the end of treatment, it should be at very low or undetectable levels in the blood. If concentrations do not fall to very low levels, then the treatment has not been fully effective. Following treatment, the PSA test is performed at regular intervals to monitor the patient for recurrence. Since even tiny increases can be significant, patients may want to have their monitoring PSA tests done by the same laboratory each time so that testing variation is kept to a minimum.

Is there anything else I should know? 
Prostate manipulation by biopsy or resection of the prostate will significantly elevate PSA levels. The blood test should be done before surgery or six weeks after manipulation.

Rigorous physical activity affecting the prostate, such as bicycle riding, may cause a temporary rise in PSA levels. Excessive doses of some chemotherapeutic drugs, such as cyclophosphamide and methotrexate, may increase or decrease PSA levels.

In some men, PSA may rise temporarily due to other prostate conditions, especially infection. A recent study found that in about half of men with a high PSA, values later return to normal. Some authorities recommend that a high PSA should be repeated (between 6 weeks and 3 months after the high PSA) before taking any further action. Some physicians will prescribe a course of antibiotics if there is evidence that there is infection of the prostate.

Insulin Levels Testing

Insulin may be used, often along with glucose and C-peptide levels, to help diagnose insulinomas and to help diagnose documented acute or chronic (fasting) hypoglycemia. Insulin and C-peptide levels may also be used to monitor endogenous (produced by the body) insulin, check for insulin resistance, and to help determine when a type 2 diabetic might need to start taking insulin injections to supplement oral medications.

Insulin levels are sometimes used in conjunction with the glucose tolerance test (GTT). In this situation, blood glucose and insulin levels are measured at pre-established time intervals to evaluate insulin resistance, particularly in obese individuals.

When is Insulin Level Testing ordered? 
Insulin levels are most frequently ordered following an abnormal glucose test and/or when a patient has acute or chronic symptoms of hypoglycemia, such as sweating, palpitations, hunger, confusion, blurred vision, dizziness, fainting, and seizures (although these can be caused by other conditions along with low blood glucose).

Insulin and C-peptide are produced by the body at the same rate as part of the activation and division of proinsulin in the pancreas. Both may be ordered to evaluate how much insulin in the blood is due to endogenous production (what your body is making) and how much is from exogenous (produced outside the body) sources. Insulin tests will reflect the total, while C-peptide will reflect only the endogenous insulin.

Your doctor also may order both tests to verify that an insulinoma has been successfully removed. If you are one of the few people who have received an islet cell transplant to restore your insulin-producing capability, your insulin level may be monitored to determine whether or not this procedure is successful over time.

What does the Insulin Level test result mean? 
report (see a sample report) should include a range of numbers (reference range) that identifies what is expected for you based on your age, sex, and the method used in that laboratory. You can find more information about expected results at Reference Ranges and What They Mean. Lab Tests Online strongly recommends that you discuss the meaning of your test results with your doctor.

Insulin levels must be evaluated in context.

Results seen:

Disorder	Fasting Insulin level	Fasting Glucose level
None	normal	normal
Insulin resistance	↑↑	normal or ↑
Not enough insulin produced by the beta cells (as seen in diabetes, pancreatitis, for example)	↓↓	↑↑
Hypoglycemia due to excess insulin (may be seen in insulinomas, Cushings, etc.)	normal or ↑↑	↓↓

Elevated insulin levels are seen with:



Decreased insulin levels are seen with:



Is there anything else I should know? 
Insulin for injection used to come strictly from animal sources (cow and pig pancreas cells). Most insulin used today is synthetic, made by biochemical synthesis to identically match the insulin produced from human cells.

There are different pharmaceutical formulations of insulin with different properties. Some are rapid-release and quick-acting and others are slow-release preparations that act over a prolonged period. Diabetics may take mixtures and/or different types of insulin throughout the day.

Insulin assays are designed to measure endogenous human insulin. However, different assays react variably with exogenous (animal or synthetic) insulin. If you are receiving insulin, these effects should be clarified with the testing laboratory. If you are going to have several insulin assays done, they should be performed by the same laboratory to ensure consistency.

The insulin tolerance test (ITT) is not widely used, but is one method for determining insulin sensitivity (or resistance) especially in obese individuals and those with PCOS. This test involves an IV-infusion of insulin, with subsequent measurements of glucose and insulin levels.

If you have developed antibodies against insulin, especially as a result of taking non-human (animal or synthetic) insulin, they can interfere with your test. Your doctor and the testing laboratory must determine if they are affecting your test result.

Complete Blood Count Screening Test (CBC) With Differential

The CBC is used as a broad screening test to check for such disorders as anemia, infection, and many other diseases. It is actually a panel of tests that examines different parts of the blood and includes the following



When is a Complete Blood Count (CBC) test ordered? 
The CBC is a very common test. Many patients will have baseline CBC tests to help determine their general health status. If they are healthy and they have cell populations that are within normal limits, then they may not require another CBC until their health status changes or until their doctor feels that it is necessary.

If a patient is having symptoms such as fatigue or weakness or has an infection, inflammation, bruising, or bleeding, then the doctor may order a CBC to help diagnose the cause. Significant increases in WBCs may help confirm that an infection is present and suggest the need for further testing to identify its cause. Decreases in the number of RBCs (anemia) can be further evaluated by changes in size or shape of the RBCs to help determine if the cause might be decreased production, increased loss, or increased destruction of RBCs. A platelet count that is low or extremely high may confirm the cause of excessive bleeding or clotting and can also be associated with diseases of the bone marrow such as leukemia.

Many conditions will result in increases or decreases in the cell populations. Some of these conditions may require treatment, while others will resolve on their own. Some diseases, such as cancer (and chemotherapy treatment), can affect bone marrow production of cells, increasing the production of one cell at the expense of others or decreasing overall cell production. Some medications can decrease WBC counts while some vitamin and mineral deficiencies can cause anemia. The CBC test may be ordered by the doctor on a regular basis to monitor these conditions and drug treatments.

What does the Complete Blood Count (CBC) test result mean? 
NOTE: This test has no single number that identifies an abnormal result. Your lab report (see a sample report) should include a range of numbers (reference range) that identifies what is expected for you based on your age, sex, and the method used in that laboratory. You can find more information about expected results at Reference Ranges and What They Mean. Lab Tests Online strongly recommends that you discuss the meaning of your test results with your doctor.

The following table explains what increases or decreases in each of the components of the CBC may mean. To download an expanded, printable version of this table, click here.

Test	Name	Increased/Decreased
WBC	White Blood Cell	May be increased with infections, inflammation, cancer, leukemia; decreased with some medications (such as methotrexate), some autoimmune conditions, some severe infections, bone marrow failure, and congenital marrow aplasia (marrow doesn't develop normally)
% Neutrophil	Neutrophil/Band/Seg/Gran	This is a dynamic population that varies somewhat from day to day depending on what is going on in the body. Significant increases in particular types are associated with different temporary/acute and/or chronic conditions. An example of this is the increased number of lymphocytes seen with lymphocytic leukemia. For more information, see Blood Smear and WBC.
% Lymphs	Lymphocyte
% Mono	Monocyte
% Eos	Eosinophil
% Baso	Basophil
Neutrophil	Neutrophil/Band/Seg/Gran
Lymphs	Lymphocyte
Mono	Monocyte
Eos	Eosinophil
Baso	Basophil
RBC	Red Blood Cell	Decreased with anemia; increased when too many made and with fluid loss due to diarrhea, dehydration, burns
Hgb	Hemoglobin	Mirrors RBC results
Hct	Hematocrit	Mirrors RBC results
MCV	Mean Corpuscular Volume	Increased with B12 and Folate deficiency; decreased with iron deficiency and thalassemia
MCH	Mean Corpuscular Hemoglobin	Mirrors MCV results
MCHC	Mean Corpuscular Hemoglobin Concentration	May be decreased when MCV is decreased; increases limited to amount of Hgb that will fit inside a RBC
RDW	RBC Distribution Width	Increased RDW indicates mixed population of RBCs; immature RBCs tend to be larger
Platelet	Platelet	Decreased or increased with conditions that affect platelet production; decreased when greater numbers used, as with bleeding; decreased with some inherited disorders (such as Wiskott-Aldrich, Bernard-Soulier), with Systemic lupus erythematosus, pernicious anemia, hypersplenism (spleen takes too many out of circulation), leukemia, and chemotherapy
MPV	Mean Platelet Volume	Vary with platelet production; younger platelets are larger than older ones

Is there anything else I should know? 
While no specific pre-testing restrictions are necessary, it is best to avoid a fatty meal prior to having your blood drawn.

Normal CBC values for babies and children may be different from adults and need to be considered when interpreting data.

Urinalysis Screen - Routine With Microscopic Examination on Positives

The urinalysis is used as a screening and/or diagnostic tool because it can help detect substances or cellular material in the urine associated with different metabolic and kidney disorders. It is ordered widely and routinely to detect any abnormalities that should be followed up on. Often, substances such as protein or glucose will begin to appear in the urine before patients are aware that they may have a problem. It is used to detect urinary tract infections (UTI) and other disorders of the urinary tract. In patients with acute or chronic conditions, such as kidney disease, the urinalysis may be ordered at intervals as a rapid method to help monitor organ function, status, and response to treatment.

When is a Urinalysis screen ordered? 
A routine urinalysis may be done when you are admitted to the hospital. It may also be part of a wellness exam, a new pregnancy evaluation, or a work-up for a planned surgery. A urinalysis will most likely be performed if you see your health care provider complaining of abdominal pain, back pain, painful or frequent urination, or blood in the urine, symptoms of a UTI. This test can also be useful in monitoring whether a condition is getting better or worse

What does the Urinalysis screen result mean? 
NOTE: This test has no single number that identifies an abnormal result. Your lab report (see a sample report) should include a range of numbers (reference range) that identifies what is expected for you based on your age, sex, and the method used in that laboratory. You can find more information about expected results at Reference Ranges and What They Mean. Lab Tests Online strongly recommends that you discuss the meaning of your test results with your doctor

Urinalysis results can have many interpretations. They are a red flag, a warning that something may be wrong and should be evaluated further. Generally, the greater the concentration of the abnormal substance (such as greatly increased amounts of glucose, protein, or red blood cells), the more likely it will be that there is a problem that needs to be addressed. But the results do not tell the doctor exactly what the cause of the finding is or whether it is a temporary or chronic condition. A normal urinalysis also does not guarantee that there is no illness. Some people will not release elevated amounts of a substance early in a disease process and some will release them sporadically during the day (which means they may be missed by a single urine sample). In very dilute urine, small quantities of chemicals may be undetectable.

Is there anything else I should know? 
The urinalysis is a set of screening tests that can provide a general overview of a person’s health. Your doctor must correlate the urinalysis results with your health complaints and clinical findings and search for the causes of abnormal findings with other targeted tests (such as a comprehensive metabolic panel (CMP), complete blood count (CBC), or urine culture (to look for a urinary tract infection).

Is there anything else I should know? 
Hemoglobin decreases slightly during normal pregnancy.

Hemoglobin levels peak around 8 a.m. and are lowest around 8 p.m. each day.

Heavy smokers have higher hemoglobin levels than nonsmokers.

Living in high altitudes increases hemoglobin values due to an increase in the number of red blood cells. Your body produces more red blood cells in response to the decreased oxygen available at these heights.

Hemoglobin levels are slightly lower in older men and women and in children.

Hemoglobin Test (Hgb) A1c

The A1c test and eAG calculation are used primarily to monitor the glucose control of diabetics over time. The goal of those with diabetes is to keep their blood glucose levels as close to normal as possible. This helps to minimize the complications caused by chronically elevated glucose levels, such as progressive damage to body organs like the kidneys, eyes, cardiovascular system, and nerves. The A1c test and eAG result give a picture of the average amount of glucose in the blood over the last few months. They can help you and your doctor know if the measures you are taking to control your diabetes are successful or need to be adjusted.

The A1c test is frequently used to help newly diagnosed diabetics determine how elevated their uncontrolled blood glucose levels have been. It may be ordered several times while control is being achieved, and then several times a year to verify that good control is being maintained.

When is the Hemoglobin (A1c) test ordered? 
Depending on the type of diabetes that you have, how well your diabetes is controlled, and your doctor, your A1c may be measured 2 to 4 times each year. The American Diabetes Association recommends testing your A1c at least twice a year. When someone is first diagnosed with diabetes or if control is not good, A1c may be ordered more frequently.

What does the Hemoglobin (A1c) test result mean? 
A1c is currently reported as a percentage, and it is recommended that diabetics aim to keep their A1c below 7%. The report for your A1c test also may include an estimated Average Glucose (eAG), which is a calculated result based on your A1c levels. The purpose of reporting eAG is to help you relate your A1c results to your everyday glucose monitoring levels. The formula for eAG converts percentage A1c to units of mg/dL or mmol/L so that you can compare it to your glucose levels from home monitoring systems or laboratory tests.

It should be noted that the eAG is still an evaluation of your glucose over the last couple of months. It will not match up exactly to any one daily glucose test result. The American Diabetes Association has adopted this calculation and provides a calculator and information on the eAG on their web site.

A nondiabetic person will have an A1c between 4% and 6%. The closer a diabetic can keep their A1c to 6% without experiencing excessive hypoglycemia, the better their diabetes is in control. As the A1c and eAG increase, so does the risk of complications.

Is there anything else I should know? 
The A1c test will not reflect temporary, acute blood glucose increases or decreases. The glucose swings of someone who has “brittle” diabetes will not be reflected in the A1c.

If you have a hemoglobin variant, such as sickle cell hemoglobin (hemoglobin S), you will have a decreased amount of hemoglobin A. This may limit the usefulness of the A1c test in monitoring your diabetes. If you have anemia, hemolysis, or heavy bleeding, your test results may be falsely low. If you are iron deficient, you may have an increased A1c measurement. If you have had a recent transfusion, then your A1c will be falsely increased (blood preservative solutions contain high glucose levels) and not accurately reflect your glucose control for 2 to 3 months.

NMR LipoProfile Test

The NMR LipoProfile® test provides a more accurate picture of a patient’s cardiovascular (CVD) risk over the standard lipid panel. A major study showed that 50% of the people who suffered a heart attack had normal cholesterol levels.

Unlike traditional cholesterol tests or lipid panels, the NMR LipoProfile® test uses NMR spectroscopy to measure the actual number of atherogenic LDL particles (LDL–P) that build up in the arteries and cause heart disease. Patients with a high number of LDL particles (LDL-P) are at increased risk for heart disease, which can lead to a heart attack, even if they have "normal" cholesterol levels. By knowing how many of these particles are circulating in the blood, a physician can get a more accurate picture of a patient's heart health and therefore make better patient care decisions.

Homocysteine Screen

Homocysteine is commonly used as a screen for people at high risk for heart attack or stroke. It may be useful in patients who have a family history of coronary artery disease but no other known risk factors. However, its utility for this purpose continues to be questioned because the role, if any, that homocysteine plays in the progression of cardiovascular disease (CVD) has not been established. Routine screening, such as that done for total cholesterol, is not yet recommended.

A physician may also order a homocysteine test to determine if a patient has B12 or folate deficiency. The homocysteine concentration may be elevated in patients before B12 and folate tests are abnormal. Some doctors may recommend homocysteine testing in malnourished patients, such as the elderly (who often absorb less vitamin B12 from their diets), and those with drug or alcohol addictions.

A doctor may order both a urine and blood homocysteine to help diagnose homocystinuria if they suspect that an infant may have this inherited disorder. In some states, babies are tested for excess methionine as part of their newborn screening. If a baby’s test is positive, then urine and blood homocysteine tests are often performed to confirm the findings.

Urine and/or blood homocysteine concentrations may be ordered at intervals to monitor the effectiveness of treatment in patients who are being treated for elevated homocysteine.

When is the Homocysteine screen ordered? 
Homocysteine may be ordered as part of a cardiac risk assessment, depending on the patient’s age and other risk factors. It may also be ordered following a heart attack or stroke to help guide treatment. It may also be ordered when a doctor suspects that a patient may have a B12 and/or folate deficiency or when a baby has signs or symptoms that suggest that they may have homocystinuria.

What does the Homocysteine test result mean? 
NOTE: This test has no single number that identifies an abnormal result. Your lab report (see a sample report) should include a range of numbers (reference range) that identifies what is expected for you based on your age, sex, and the method used in that laboratory. You can find more information about expected results at Reference Ranges and What They Mean. Lab Tests Online strongly recommends that you discuss the meaning of your test results with your doctor.

Recent studies have suggested that people who have elevated homocysteine levels have a much greater risk of heart attack or stroke than those with average levels. At present, however, the American Heart Association has not established a direct correlation between homocysteine levels and heart attacks but does acknowledge strong evidence of a relationship between homocysteine levels and heart attack/stroke survival rates. Blockage of a coronary artery, a precursor to a heart attack, occurs with more than double the average frequency in people with homocysteine levels in the highest 25% as compared to those in the lowest 25%.

Since measuring homocysteine levels to determine cardiac risk is a relatively new use for the test, a standardized interpretation of the measured value has yet to be determined. In many people, homocysteine levels can be decreased by taking extra levels of folic acid, vitamin B12, and vitamin B6 - three B-complex vitamins that drive homocysteine metabolism. The elderly are especially vulnerable and may need these supplements to keep their homocysteine levels low.

Greatly increased concentrations of homocysteine in the urine and blood mean that it is likely that an infant has homocystinuria and indicate the need for further testing to confirm the cause of the increase.

Is there anything else I should know? 
When test results suggest homocystinuria, liver or skin biopsy samples are sometimes tested to determine whether the enzyme cystathionine beta synthase (CBS) is present. The absence of this enzyme is the most common cause of homocystinuria. Genetic tests may be ordered to test for one or more of the most common gene mutations. If the patient has a strong family history of early atherosclerosis or a family member has been diagnosed with homocystinuria, then the patient should be tested for the gene mutation that was found in the family member.

Homocysteine levels can increase with age, when a patient smokes, and with the use of drugs such as carbamazepine, methotrexate, and phenytoin.

Lipoprotein-associated Phospholipase A2 - Lp-PLA (PLAC)

The Food and Drug Administration (FDA) recently cleared for marketing a new laboratory blood test that will increase the ability of doctors to predict the risk of coronary heart disease (CHD).

The test, called PLAC, works by measuring an enzyme called lipoprotein-associated phospholipase A2. This enzyme is made by a type of white blood cell called a macrophage. Macrophages make more of this enzyme and release it into the blood when a person has CHD.

FDA cleared the test based on results of a study of more than 1,348 patients. The study was a part of a large multi-center epidemiologic study sponsored by the National Heart, Lung, and Blood Institute. Patients were free from CHD at the start of the study and were followed for the development of disease for nine years. The greatest increased risk was found in subjects with the highest PLAC test results and LDL cholesterol levels lower than 130mg/dL.