The Test Sample
What is being tested?
The comprehensive metabolic panel (CMP) is a frequently ordered panel of 14 tests that gives a healthcare provider important information about the current status of a person's kidneys and liver, electrolyte and acid/base balance as well as levels of blood glucose and blood proteins. Abnormal results, and especially combinations of abnormal results, can indicate a problem that needs to be addressed.
The CMP includes the following tests:
- Glucose - energy source for the body; a steady supply must be available for use, and a relatively constant level of glucose must be maintained in the blood.
- Calcium - one of the most important minerals in the body; essential for the proper functioning of muscles, nerves, and the heart and is required in blood clotting and in the formation of bones
- Albumin - a small protein produced in the liver; the major protein in serum
- Total Protein - measures albumin as well as all other proteins in serum
- Sodium - vital to normal body processes, including nerve and muscle function
- Potassium - vital to cell metabolism and muscle function
- CO2 (carbon dioxide, bicarbonate) - helps to maintain the body's acid-base balance (pH)
- Chloride - helps to regulate the amount of fluid in the body and maintain the acid-base balance
- BUN (blood urea nitrogen) - waste product filtered out of the blood by the kidneys; conditions that affect the kidney have the potential to affect the amount of urea in the blood.
- Creatinine - waste product produced in the muscles; filtered out of the blood by the kidneys so blood levels are a good indication of how well the kidneys are working
- ALP (alkaline phosphatase) - enzyme found in the liver and other tissues, bone; elevated levels of ALP in the blood are most commonly caused by liver disease or bone disorders.
- ALT (alanine amino transferase, also called SGPT) - enzyme found mostly in the cells of the liver and kidney; a useful test for detecting liver damage
- AST (aspartate amino transferase, also called SGOT) - enzyme found especially in cells in the heart and liver; also a useful test for detecting liver damage
- Bilirubin - waste product produced by the liver as it breaks down and recycles aged red blood cells
How is the sample collected for testing?
A blood sample is obtained by inserting a needle into a vein in the arm.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
You may need to fast (nothing but water) for 10 to 12 hours prior to the blood draw. Depending on the reason for ordering the CMP, it may be drawn after fasting or on a random basis.