CMP -14 Test

The Comprehensive Metabolic Panel (CMP) is typically a group of 14 specific tests that have been approved, named, and assigned a CPT code (a Current Procedural Terminology number) as a panel by Medicare (although labs may adjust the number of tests up or down). Since the majority of insurance companies also use these names and CPT codes in their claim processing, this grouping of tests has become standardized throughout the United States. The CMP is a frequently ordered panel that gives your doctor important information about the current status of your kidneys, liver, and electrolyte and acid/base balance as well as of your blood sugar and blood proteins. Abnormal results, and especially combinations of abnormal results, can indicate a problem that needs to be addressed.

The CMP is used as a broad screening tool to evaluate organ function and check for conditions such as diabetes, liver disease, and kidney disease. The CMP may also be ordered to monitor known conditions, such as hypertension, and to monitor patients taking specific medications for any kidney- or liver-related side effects. If your doctor is interested in following two or more individual CMP components, he may order the entire CMP because it offers more information.

The CMP is routinely ordered as part of a blood work-up for a medical exam or yearly physical and is collected by inserting a needle into a vein in your arm. Although it may be performed on a random basis, the CMP sample is usually collected after a 10 to 12 hour fast (no food or liquids other than water). While the individual tests are sensitive, they do not usually tell your doctor specifically what is wrong. Abnormal test results or groups of test results are usually followed-up with other specific tests to confirm or rule out a suspected diagnosis.

The CMP includes:


Both increased and decreased levels can be significant.

Proteins


Albumin, a small protein produced in the liver, is the major protein in serum. Total protein measures albumin as well as all other proteins in serum. Both increases and decreases in these test results can be significant.

Electrolytes


The concentrations of sodium and potassium are tightly regulated by the body as is the balance between the four tests. Electrolyte (and acid-base) imbalances can be present with a wide variety of acute and chronic illnesses. Chloride and CO2 tests are rarely ordered by themselves.

Kidney Tests


BUN and creatinine are waste products filtered out of the blood by the kidneys. Increased concentrations in the blood may indicate a temporary or chronic decrease in kidney function. When not ordered as part of the CMP, they are still usually ordered together.

Liver Tests


ALP, ALT, and AST are enzymes found in the liver and other tissues, while bilirubin is a waste product of the liver. All can be found in elevated concentrations in the blood with liver disease or dysfunction.

Lipid Profile Tests

The lipid profile is a group of tests that are often ordered together to determine risk of coronary heart disease. They are tests that have been shown to be good indicators of whether someone is likely to have a heart attack or stroke caused by blockage of blood vessels or hardening of the arteries (atherosclerois). The lipid profile typically includes:


An extended profile may also include:
• Very low density lipoprotein cholesterol (VLDL-C)

Sometimes the report will include additional calculated values such as the Cholesterol/HDL ratio or a risk score based on lipid profile results, age, sex, and other risk factors.

How is the Lipid Profile sample collected for testing? 
A blood sample is obtained by inserting a needle into a vein in the arm. Sometimes a drop of blood is collected by puncturing the skin on a fingertip. This fingerstick sample is typically used when a lipid profile is being measured on a portable testing device, for example, at a health fair. You need to fast for 9-12 hours before having your blood drawn; only water is permitted.

How is a lipid profile test used? 
The lipid profile is used to help determine your risk of heart disease and to help guide you and your health care provider in deciding what treatment may be best for you if you have borderline or high risk. The results of the lipid profile are considered along with other known risk factors of heart disease to develop a plan of treatment and follow-up. Depending on your results and other risk factors, treatment options may involve life-style changes such as diet and exercise or lipid-lowering medications such as statins.

When is the Lipid Profile Test ordered? 
It is recommended that healthy adults with no other risk factors for heart disease be tested with a fasting lipid profile once every five years. You may be screened using only a cholesterol test and not a full lipid profile. However, if the cholesterol test result is high, you may have follow-up testing with a lipid profile.

If you have other risk factors or have had a high cholesterol level in the past, you should be tested more regularly and you should have a full lipid profile.

For children and adolescents at low risk, lipid testing is usually not ordered routinely. However, screening with a lipid profile is recommended for children and youths who are at an increased risk of developing heart disease as adults. Some of the risk factors are similar to those in adults and include a family history of heart disease or health problems such as diabetes, high blood pressure (hypertension), or being overweight. High-risk children should have their first lipid profile between 2 and 10 years old, according to the American Academy of Pediatrics. Children younger than 2 years old are too young to be tested.

A lipid profile may also be ordered at regular intervals to evaluate the success of lipid-lowering lifestyle changes such as diet and exercise or to determine the effectiveness of drug therapy such as statins.

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.

AIf 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.

Blood Glucose Test

The blood glucose test is ordered to measure the amount of glucose in the blood right at the time of sample collection. It is used to detect both hyperglycemia and hypoglycemia, to help diagnose diabetes, and to monitor glucose levels in persons with diabetes. Blood glucose may be measured on a fasting basis (collected after an 8 to 10 hour fast), randomly (anytime), post prandial (after a meal), and/or as part of an oral glucose tolerance test (OGTT / GTT). An OGTT is a series of blood glucose tests. A fasting glucose is collected; then the patient drinks a standard amount of a glucose solution to "challenge" their system. This is followed by one or more additional glucose tests performed at specific intervals to track glucose levels over time. The OGTT may be ordered to help diagnose diabetes and as a follow-up test to an elevated blood glucose.

The American Diabetes Association recommends either the fasting glucose or the OGTT to diagnose diabetes but says that testing should be done twice, at different times, in order to confirm a diagnosis of diabetes.

Most pregnant women are screened for gestational diabetes, a temporary form of hyperglycemia, between their 24th and 28th week of pregnancy using a version of the OGTT, a 1-hour glucose challenge. If either fasting glucose or a random glucose is above the values used to diagnose diabetes in those who are not pregnant, the woman is considered to have gestational diabetes and neither the screening nor the glucose tolerance test is needed. If the 1-hour level is higher than the defined value, a longer OGTT is performed to clarify the patient’s status.

Diabetics must monitor their own blood glucose levels, often several times a day, to determine how far above or below normal their glucose is and to determine what oral medications or insulin(s) they may need. This is usually done by placing a drop of blood from a skin prick onto a glucose strip and then inserting the strip into a glucose meter, a small machine that provides a digital readout of the blood glucose level.

In those with suspected hypoglycemia, glucose levels are used as part of the "Whipple triad" to confirm a diagnosis. (See “Is there anything else I should know?” section).

The urine glucose is seldom ordered by itself. At one time, it was used to monitor diabetics, but it has been largely replaced by the more sensitive and “real time” blood glucose. The urine glucose is, however, one of the substances measured when a urinalysis is performed. A urinalysis may be done routinely as part of a physical or prenatal checkup, when a doctor suspects that a patient may have a urinary tract infection, or for a variety of other reasons. The doctor may follow an elevated urine glucose test with blood glucose testing.

When is the Blood Glucose test ordered? 
Blood glucose testing can be used to screen healthy, asymptomatic individuals for diabetes and pre-diabetes because diabetes is a common disease that begins with few symptoms. Screening for glucose may occur during public health fairs or as part of workplace health programs. It may also be ordered when a patient has a routine physical exam. Screening is especially important for people at high risk of developing diabetes, such as those with a family history of diabetes, those who are overweight, and those who are more than 40 to 45 years old.

The glucose test may also be ordered to help diagnose diabetes when someone has symptoms of hyperglycemia, such as:


or symptoms of hypoglycemia, such as:


Blood glucose testing is also done in emergency settings to determine if low or high glucose is contributing to symptoms such as fainting and unconsciousness. If a patient has pre-diabetes (characterized by fasting or OGTT levels that are higher than normal but lower than those defined as diabetic), the doctor will order a glucose test at regular intervals to monitor the patient’s status. With known diabetics, doctors will order glucose levels in conjunction with other tests such as hemoglobin A1c to monitor glucose control over a period of time. Occasionally, a blood glucose level may be ordered along with insulin and C-peptide to monitor insulin production.

Diabetics may be required to self-check their glucose, once or several times a day, to monitor glucose levels and to determine treatment options as prescribed by their doctor.

Pregnant women are usually screened for gestational diabetes late in their pregnancies, unless they have early symptoms or previously have had gestational diabetes. When a woman has gestational diabetes, her doctor will usually order glucose levels throughout the rest of her pregnancy and after delivery to monitor her condition.

What does the Blood Glucose test result mean? 
High levels of glucose most frequently indicate diabetes, but many other diseases and conditions can also cause elevated glucose. The following information summarizes the meaning of the test results. These are based on the clinical practice recommendations of the American Diabetes Association.

Fasting Blood Glucose
From 70 to 99 mg/dL (3.9 to 5.5 mmol/L)	Normal fasting glucose
From 100 to 125 mg/dL (5.6 to 6.9 mmol/L)	Impaired fasting glucose (pre-diabetes)
126 mg/dL (7.0 mmol/L) and above on more than one testing occasion	Diabetes

Oral Glucose Tolerance Test (OGTT) [except pregnancy] (2 hours after a 75-gram glucose drink)
Less than 140 mg/dL (7.8 mmol/L)	Normal glucose tolerance
From 140 to 200 mg/dL (7.8 to 11.1 mmol/L)	Impaired glucose tolerance (pre-diabetes)
Over 200 mg/dL (11.1 mmol/L) on more than one testing occasion	Diabetes

Gestational Diabetes Screening: Glucose Challenge Test (1 hour after a 50-gram glucose drink)
Less than 140* mg/dL (7.8 mmol/L)	Normal screen
140* mg/dL (7.8 mmol/L) and over	Abnormal, needs OGTT (see below)
* Some use a cutoff of >130 mg/dL (7.2 mmol/L) because that identifies 90% of women with gestational diabetes, compared to 80% identified using the threshold of >140 mg/dL (7.8 mmol/L).

Gestational Diabetes Diagnostic: OGTT (100-gram glucose drink)
Fasting*	95 mg/dL (5.3 mmol/L)
1 hour after glucose load*	180 mg/dL (10.0 mmol/L)
2 hours after glucose load*	155 mg/dL (8.6 mmol/L)
3 hours after glucose load* **	140 mg/dL (7.8 mmol/L)
* If two or more values are above the criteria, gestational diabetes is diagnosed. ** A 75-gram glucose load may be used, although this method is not as well validated as the 100-gram OGTT; the 3-hour sample is not drawn if 75 grams is used.

Some of the other diseases and conditions that can result in elevated glucose levels include:


Low to non-detectible urine glucose results are considered normal. Anything that raises blood glucose levels also has the potential to elevate urine glucose levels. Increased urine glucose levels may be seen with medications, such as estrogens and chloral hydrate, and with some forms of renal disease.

Moderately increased blood levels may be seen with pre-diabetes. This condition, if left un-addressed, often leads to type 2 diabetes.

Low blood glucose levels (hypoglycemia) are also seen with:


Is there anything else I should know? 
Hypoglycemia is characterized by a drop in blood glucose to a level where first it causes nervous system symptoms (sweating, palpitations, hunger, trembling, and anxiety), then begins to affect the brain (causing confusion, hallucinations, blurred vision, and sometimes even coma and death). An actual diagnosis of hypoglycemia requires satisfying the "Whipple triad." These three criteria include:


Primary hypoglycemia is rare and often diagnosed in infancy. People may have symptoms of hypoglycemia without really having low blood sugar. In such cases, dietary changes such as eating frequent small meals and several snacks a day and choosing complex carbohydrates over simple sugars may be enough to ease symptoms. Those with fasting hypoglycemia may require IV glucose if dietary measures are insufficient.

Thyroid-stimulating hormone (TSH) Test

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 the TSH 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.

Electrolyte Panel Testing

T3 uptake (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 the T3 uptake (THBR) 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 (THBR) 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.

Thyroxine (T4) Testing

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 Thyroxine Testing 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 Thyroxine 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.

Complete Blood Count (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.