To determine your general health status; to screen for, diagnose, or monitor any one of a variety of diseases and conditions, such as kidney disease, liver disease, high blood pressure (hypertension) or diabetes; to monitor the use of specific medications that may affect kidney health or liver function
Comprehensive Metabolic Panel (CMP)
When you have a routine health exam as suggested by your healthcare practitioner; when you are ill or being monitored for a specific condition or side effects from certain medications
A blood sample drawn from a vein
Depending on the reason for testing, you may need to fast (drinking nothing but water) for at least 8 hours prior to the blood draw. Follow any instructions you are given by your healthcare practitioner. Be sure your healthcare practitioner knows about all prescription and over-the counter medicines, herbs, vitamins, and supplements you are taking.
The comprehensive metabolic panel (CMP) is a group of 14 tests that measures several different substances in your blood. It is one of the most commonly ordered lab tests.
The CMP gives your healthcare practitioner important information about the current status of your body's metabolism (hence the name metabolic panel). The CMP provides information on your blood sugar (glucose) levels, the balance of electrolytes and fluid as well as the health of your kidneys and liver. Abnormal results, and especially combinations of abnormal results, can indicate a problem that needs to be addressed and may require additional testing.
The CMP includes the following tests:
- Glucose - the primary energy source for the body's cells; a steady supply must be available for use, and a relatively stable level of glucose must be maintained in the blood.
- Calcium - one of the most important minerals in the body; it is 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 made by the liver; it makes up about 60% of the total protein in the blood.
- Total Protein - measures albumin as well as all other proteins in blood; proteins are important building blocks of all cells and tissues and are essential for body growth, development, and health.
Electrolytes—these are minerals found in body tissues and blood in the form of dissolved salts. Electrolytes help move nutrients into the body's cells and help remove wastes out of the cells. They help maintain a healthy water balance and help stabilize the body's acid-base (pH) level. The following 4 tests are commonly called electrolytes:
- Sodium - vital to normal body function, including nerve and muscle function
- Potassium - vital to cell metabolism and muscle function, helping to transmit messages between nerves and muscles
- Bicarbonate (Total CO2) - 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
- Blood urea nitrogen (BUN) - waste product filtered out of the blood by the kidneys; as kidney function decreases, the BUN level rises.
- Creatinine - waste product produced in the muscles; it is filtered out of the blood by the kidneys so blood levels are a good indication of how well the kidneys are working.
- Alkaline phosphatase (ALP) - enzyme found in bone, the liver, and other tissues; elevated levels of ALP in the blood are most commonly caused by liver disease or bone disorders.
- Alanine amino transferase (ALT, SGPT) - enzyme found mostly in the cells of the liver and kidney; a useful test for detecting liver damage
- Aspartate amino transferase (AST, SGOT) - enzyme found especially in cells in the heart and liver; also a useful test for detecting liver damage
- Bilirubin - an orange-yellow pigment, a waste product primarily produced by the normal breakdown of heme; heme is a component of hemoglobin, which is found in red blood cells (RBCs). Bilirubin is ultimately processed by the liver so that it can be removed from the body.
How is the test used?
The comprehensive metabolic panel (CMP) is used as a broad screening tool to evaluate the health of your organs and to screen for conditions such as diabetes, liver disease, and kidney disease. The CMP may also be ordered to monitor known conditions, such as high blood pressure (hypertension), and to monitor treatment with specific medications that may affect kidney or liver function. If your healthcare practitioner is interested in monitoring two or more individual CMP components, your practitioner may order the entire CMP because it offers more information.
When is it ordered?
The CMP may be ordered when you have a routine health exam. The panel is often ordered as part of a medical exam when you are ill, in the hospital, or in the emergency department. CMPs may be ordered regular intervals when you have an ongoing or long-term condition that is being monitored or when you are taking specific medication that may affect liver or kidney function.
What does the test result mean?
Results of the tests that are part of the CMP are typically evaluated together to look for patterns of results. A single abnormal test result may mean something different than if several test results are abnormal. For example, a high result on just one of the liver enzyme tests has different implications than high results on several liver enzyme tests.
Sometimes, especially in hospitalized patients, several sets of CMPs, often performed on different days, may be evaluated to gain insights into the underlying condition and response to treatment.
The results report will usually have one column called a "reference range" and another for your results. Results that fall outside the reference range for any of the tests in the CMP can be due to a variety of different conditions.
While the individual tests are sensitive, they do not usually tell your healthcare practitioner specifically what is wrong. Abnormal test results or groups of test results are usually followed up with other specific tests to help confirm or rule out a suspected diagnosis.
See the articles on the individual tests for more detailed information about each one.
Are these tests always run as a panel?
No. Each of these tests may be ordered individually. However, if your healthcare practitioner is interested in following two or more individual CMP components, your practitioner may order the entire CMP because it offers more information. Alternatively, a healthcare provider may order individual tests when monitoring specific conditions.
How is the CMP different than the BMP and why would my doctor order one over the other?
The CMP typically includes 14 tests. The basic metabolic panel (BMP) is a subset of the CMP and usually includes 8 tests. It does not include the liver tests (ALP, ALT, AST, and bilirubin) and protein tests (albumin and total protein). Healthcare practitioners may order a CMP rather than a BMP if they want to get a more complete picture of the health of your organs or to check for specific conditions, such as diabetes, liver disease, or kidney disease.
One of the results from my CMP is slightly out of range. What does this mean?
The results of your CMP are interpreted by your healthcare provider within the context of other tests that you have had done as well as other factors, such as your medical history. A single result that is slightly high or low may or may not have medical significance. There are several reasons why a test result may differ on different days and why it may fall outside a designated reference range.
- Biological variability (different results in the same person at different times): If a healthcare practitioner runs the same test on you on several different occasions, there's a good chance that one result will fall outside a reference range even though you are in good health. For biological reasons, your values can vary from day to day.
- Individual variability (differences in results between different people): References ranges are usually established by collecting results from a large population and determining from the data an expected average (mean) result and expected differences from that average (standard deviation). There are individuals who are healthy but whose tests results, which are normal for them, do not always fall within the expected range of the overall population.
Thus, a test value that falls outside of the established reference range supplied by the laboratory may mean nothing significant. Generally, this is the case when the test value is only slightly higher or lower than the reference range and this is why a healthcare practitioner may repeat a test on you and why the practitioner may look at results from prior times when you had the same test performed.
However, a result outside the range may indicate a problem and warrant further investigation. Your healthcare provider will evaluate your test results in the context of your medical history, physical examination, and other relevant factors to determine whether a result that falls outside of the reference range means something significant for you.
Is there anything else I should know?