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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 6 to 8 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:

• Glucose
• Calcium

• Proteins
  • Albumin
  • Total Protein
• 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
  • Sodium
  • Potassium
  • CO2 (carbon dioxide, bicarbonate)
  • Chloride
    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 (blood urea nitrogen)
    • Creatinine
    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 (alkaline phosphatase)
    • ALT (alanine amino transferase, also called SGPT)
    • AST (aspartate amino transferase, also called SGOT)
    • Bilirubin
      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.

White Blood Cells (WBCs)
There are five different types of WBCs that the body uses to fight infections or other causes of injury. These types - neutrophils, lymphocytes, basophils, eosinophils, and monocytes - are present in relatively stable percentages that may temporarily shift higher or lower depending on what is going on in the body. For instance, with an infection, there may be a higher concentration of neutrophils (a "shift to the left"). With allergies, there may be an increased number of eosinophils, and with leukemia, there may be a much higher percentage of a single type of cell, such as a lymphocyte. In this case, the cell may be present in large numbers, in a mature form and in a variety of immature forms. The CBC determines whether there are sufficient WBCs present to fight infection, notes when there are more than expected, and determines the percentages and numbers of each type.

Red Blood Cells (RBCs)
RBCs are reddish in color and shaped like a donut with a thinner section in the middle instead of a hole. They have hemoglobin inside them, a protein that transports oxygen throughout the body. The CBC determines whether there are sufficient RBCs present and whether the population of RBCs appears to be normal. RBCs are normally all the same size and shape; however, variations can occur with vitamin B12 and folate deficiencies, iron deficiency, and with a variety of other conditions. If there are insufficient normal RBCs present, the patient is said to have anemia and may have symptoms, such as fatigue and weakness. Much less frequently, there may be too many RBCs in the blood (erythrocytosis or polycythemia). In extreme cases, this can interfere with the flow of blood through the veins and arteries.

Platelets
Platelets are special cell fragments that play an important role in blood clotting. If a patient does not have enough platelets, he will be at an increased risk of excessive bleeding and bruising. The CBC measures the number and size of platelets present. With some conditions and in some people, there may be giant platelets or platelet clumps that are difficult for the hematology instrument to accurately measure. In this case, a blood smear test may be necessary.

How is the sample collected for testing?
The CBC is performed on a blood sample taken by a needle placed in a vein in the arm or by a fingerstick (for children and adults) or heelstick (for infants).

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:

• White blood cell (WBC) count is a count of the actual number of white blood cells per volume of blood. Both increases and decreases can be significant.
• White blood cell differential looks at the types of white blood cells present. There are five different types of white blood cells, each with its own function in protecting us from infection. The differential classifies a person's white blood cells into each type: neutrophils (also known as segs, PMNs, grans), lymphocytes, monocytes, eosinophils, and basophils.
• Red blood cell (RBC) count is a count of the actual number of red blood cells per volume of blood. Both increases and decreases can point to abnormal conditions.
• Hemoglobin measures the amount of oxygen-carrying protein in the blood.
• Hematocrit measures the amount of space red blood cells take up in the blood. It is reported as a percentage.
• The platelet count is the number of platelets in a given volume of blood. Both increases and decreases can point to abnormal conditions of excess bleeding or clotting. Mean platelet volume (MPV) is a machine-calculated measurement of the average size of your platelets. New platelets are larger, and an increased MPV occurs when increased numbers of platelets are being produced. MPV gives your doctor information about platelet production in your bone marrow.
• Mean corpuscular volume (MCV) is a measurement of the average size of your RBCs. The MCV is elevated when your RBCs are larger than normal (macrocytic), for example in anemia caused by vitamin B12 deficiency. When the MCV is decreased, your RBCs are smaller than normal (microcytic), such as is seen in iron deficiency anemia or thalassemias.
• Mean corpuscular hemoglobin (MCH) is a calculation of the amount of oxygen-carrying hemoglobin inside your RBCs. Since macrocytic RBCs are larger than either normal or microcytic RBCs, they would also tend to have higher MCH values.
• Mean corpuscular hemoglobin concentration (MCHC) is a calculation of the concentration of hemoglobin inside the RBCs. Decreased MCHC values (hypochromia) are seen in conditions where the hemoglobin is abnormally diluted inside the red cells, such as in iron deficiency anemia and in thalassemia. Increased MCHC values (hyperchromia) are seen in conditions where the hemoglobin is abnormally concentrated inside the red cells, such as in hereditary spherocytosis, a relatively rare congenital disorder.
• Red cell distribution width (RDW) is a calculation of the variation in the size of your RBCs. In some anemias, such as pernicious anemia, the amount of variation (anisocytosis) in RBC size (along with variation in shape - poikilocytosis) causes an increase in the RDW.

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, and 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.

How is the sample collected for testing?
A blood sample obtained from a needle placed in a vein in your arm or from pricking the heel of an infant.

TSH testing is used to:

• screen adults for thyroid disorders
• diagnose a thyroid disorder in a person with symptoms,
• screen newborns for an underactive thyroid,
• monitor thyroid replacement therapy in people with hypothyroidism
• diagnose and monitor female infertility problems

What tests are included in a lipid profile?
The lipid profile includes total cholesterol, HDL-cholesterol (often called good cholesterol), LDL-cholesterol (often called bad cholesterol), and triglycerides.

How is a lipid profile used?
The lipid profile is used to guide providers in deciding how a person at risk should be treated. 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.

How is treatment determined?
Treatment is based on your overall risk of coronary heart disease. A target LDL is identified. If your LDL is above the target value, you will be treated.

The first step in treating high LDL is targeted at changes in lifestyle - specifically adopting diets low in saturated fat and participating in moderate exercise.

If low-fat diets and exercise are not adequate to lower LDL-cholesterol to the target value, drug therapy would be the next step. There are several classes of drugs that are effective in lowering LDL. You will prescribed one of these. Your LDL and liver enzymes (see AST and ALT under the CMP section for more information), will be checked at regular intervals to assure that the drug is working. If the drug does not result in reaching your target LDL-cholesterol, your doctor may increase the amount of drug or possibly add a second drug.

What are risk factors (in addition to high LDL) for coronary heart disease?
Risk factors include:

• Cigarette smoking
• Age (you are a male 45 years or older or a female 55 years or older)
• Low HDL cholesterol (less than 40 mg/dL (1.04 mmol/L) )
• Hypertension (Blood Pressure of 140/90 or higher or taking high blood pressure medications)
• Family history of premature heart disease (heart disease in a first degree male relative under age 55 or a first degree female relative under age 65)

When to get tested?
When first diagnosed with diabetes and then 2 to 4 times per year

Sample required?
A blood sample drawn from a vein in the arm or from a fingerstick

What is being tested?
The A1c test evaluates the average amount of glucose in the blood over the last 3 to 4 months. It does this by measuring the concentration of glycosylated hemoglobin. As glucose circulates in the blood, some of it spontaneously binds to hemoglobin A (the primary form of hemoglobin in adults, for more information please see the CBC section).

How is it used?
The A1c test is 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 gives a picture of the average amount of glucose in the blood over the last few months. It can help a patient and his doctor know if the measures they are taking to control the patient's diabetes are successful or need to be adjusted.

The A1c test is frequently ordered on newly diagnosed diabetics to help 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 it 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. When someone is first diagnosed with diabetes or if control is not good, A1c may be ordered more frequently.

Sample required?
A blood sample drawn from a vein in the arm.

What is being tested?
This test measures the amount of prostate specific antigen (PSA) in the blood. It was developed as a tumor marker to screen for and to monitor prostate cancer. It is a good tool, but not a perfect one. Elevated levels of PSA are associated with prostate cancer, but they may also be seen with prostatitis (inflammation of the prostate) and benign prostatic hyperplasia (BPH). Mild to moderately increased concentrations of PSA may be seen in those of African American heritage, and levels tend to increase in all men as they age.

PSA is a protein produced primarily by cells in the prostate, a small gland that encircles the urethra in males and produces a fluid that makes up part of semen. Most of the PSA that the prostate produces is released into this fluid, but small amounts of it are also released into the bloodstream.

PSA is not diagnostic of cancer. The gold standard for identifying prostate cancer is still the prostate biopsy, collecting small samples of prostate tissue and identifying abnormal cells under the microscope. The total PSA test and digital rectal exam (DRE) are used together to help determine the need for a prostate biopsy.

How is it used?
The total PSA test and digital rectal exam (DRE) are ordered to screen both asymptomatic and symptomatic men for prostate cancer. 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.

When is it ordered?
There is no consensus among the experts currently about when the PSA test should be ordered to screen asymptomatic males. 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. 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.