Comprehensive Metabolic Panel (CMP)

A comprehensive metabolic panel (CMP) is a blood test with 14 different measurements. It is often used to evaluate liver function, kidney function, and nutrient levels.

Because it includes multiple measurements, the CMP offers a broad look at different functions of the body. As a result, it may be prescribed in a number of contexts, including to help diagnose and monitor conditions like diabetes and kidney and liver disease.

Purpose of the test

The purpose of the comprehensive metabolic panel is to conduct a broad assessment of various aspects of physical well-being. With 14 measurements, it can detect a range of abnormalities in blood sugar, nutrient balance, and liver and kidney health.

Depending on the situation, a CMP can be employed for diagnosis, screening, or monitoring.

• Diagnosis happens after symptoms have started and is the process used to determine the cause. Because it includes a collection of measurements, the CMP may be prescribed in the diagnosis of many different types of symptoms.
• Screening is attempting to find health problems before symptoms occur. The CMP may be prescribed as part of a routine health check-up to look for indications of underlying issues.
• Monitoring is the process of seeing how a patient’s situation changes. A CMP can be used to see if test levels go up or down over time, including after treatment. The test can also help check for side effects of medications, especially those that have the potential to affect the liver or kidneys.

What does the test measure?

The CMP includes 14 separate measurements that are conducted with the same blood sample:

• Glucose is a type of sugar that provides energy for the brain and body. This is also known as blood sugar and may be elevated with metabolic problems like diabetes.
• Calcium is a critical mineral that enables bone health as well as the functioning of muscles and the cardiovascular and nervous systems. The main sources of calcium are dietary, but calcium levels in the blood do not normally fluctuate based on diet. Instead, calcium in the blood is usually drawn from calcium stored in the bones.
• Sodium is a type of compound known as an electrolyte. Electrolytes are minerals that promote healthy fluid levels and acid-base balance in the body. They also facilitate proper muscle and nerve function. Most sodium comes from your diet, and the kidneys help regulate your body’s sodium levels.
• Potassium is an electrolyte that is present in all tissues of the body and comes from the foods you eat.
• Bicarbonate is an electrolyte that reflects the level of carbon dioxide (CO2) in your blood.
• Chloride is another electrolyte that functions along with sodium, potassium, and bicarbonate to enable a wide range of processes in the body.
• Blood urea nitrogen (BUN) is a measurement of urea nitrogen, a waste material that the kidneys help eliminate from the blood.
• Creatinine is a byproduct of normal muscle activity. It is a waste product that is normally filtered and removed from the blood by the kidneys.
• Albumin is a protein produced in the liver that transports important substances through the body and also keeps fluid from leaking out of blood vessels.
• Total protein is a measurement of the sum of albumin and globulins, which are proteins related to blood vessel and immune function.
• Alkaline phosphatase (ALP) is an enzyme that is found in tissues throughout the body. It supports numerous biological processes and is most concentrated in the liver and bones.
• Alanine aminotransferase (ALT) is an enzyme that is primarily found in the liver.
• Aspartate aminotransferase (AST) is an enzyme present in the liver and other tissues of the body.
• Bilirubin is a waste product that is yellowish in color and is produced from the breakdown of red blood cells. The liver plays a central role in eliminating bilirubin from the body.

When should I get a comprehensive metabolic panel?

The comprehensive metabolic panel may be appropriate in a range of different circumstances. For diagnosis, it may be indicated when you have symptoms that could be related to problems affecting the kidney, liver, or metabolism. It may also be helpful when you have a general symptom, such as fatigue, that can be caused by many different health conditions.

There are no clear guidelines for when the CMP should be used for screening in people without any symptoms. While many doctors prescribe the test as part of routine check-ups, there is a lack of evidence showing that the benefits of such testing outweigh the risks, such as unnecessary costs and procedures.

For monitoring, a CMP may be prescribed if you had a prior test that was abnormal in order to see if your levels remain abnormal. A CMP can also be used after treatment has been started to see how your levels have changed. If you are starting a new medication that can alter kidney or liver function, the CMP may be a useful tool for making sure that these organs are still working properly.

How to get tested

The comprehensive metabolic panel uses a blood sample that is normally taken in a medical laboratory, office, or clinic. The test is done after being prescribed by a doctor, and the analysis is conducted in a laboratory.

Can I take the test at home?

There are no or extremely limited at-home test kit options for the full comprehensive metabolic panel. This test is almost always conducted by obtaining a sample in a lab or other medical setting.

While the full CMP is not generally offered as an at-home test kit, some of the 14 components of the panel, such as the measurements commonly included in a liver panel, may be available with an at-home kit. In these kits, you take a fingerstick blood sample and send that sample by mail to a laboratory where it can be analyzed.

How much does the test cost?

There is not a set price for the comprehensive metabolic panel. Instead, the cost depends on whether you have insurance coverage and where the blood sample is taken and analyzed.

The charges for CMP testing can involve the fees for the technician who draws your blood, the lab’s fees for analysis, and the costs for any office visits. Many health insurance plans provide at least partial coverage for these costs if they are prescribed by your doctor and care is provided within the provider’s network.

For specific details about expected costs, contact your doctor’s office and your insurance provider, and make sure to ask about any copays or deductibles that you may be responsible for paying.

A blood sample is needed for the comprehensive metabolic panel. All 14 measurements in the panel are conducted with the same sample, which is taken from a vein in your arm. This blood draw is usually done in a health clinic, doctor’s office, hospital, or laboratory.

Before the test

You may need to fast before your blood draw for a CMP. This means that you don’t eat any food and don’t have anything to drink besides water. In most cases, you will fast for 10-12 hours before the test, but you should follow any specific instructions provided by your doctor’s office.

In preparation for the test, you should also inform your doctor about any medications or dietary supplements that you regularly take. Your doctor can then tell you whether you need to adjust your medication schedule before taking your blood sample.

During the test

A blood draw is a routine procedure that generally takes less than a few minutes. While you are seated, a technician will tie an elastic band around the upper section of your arm. They will use an antiseptic to clean the part of your arm where your blood will be drawn. A needle will be inserted into your vein, and a vial of blood will be withdrawn.

You may experience some pain, often a brief sting, when the needle is inserted into and removed from your arm.

After the test

After a vial of blood has been drawn, the needle is removed to finish the procedure. The technician will usually apply a swab or bandage to stop bleeding from the puncture site. Some people find that their arm is tender or may have bruising after their blood is drawn, but serious or lasting effects are uncommon.

Because you have to fast before the test, you may want to bring something with you to eat after your blood has been drawn. After the test is over, you can drive and return to most normal activities.

Receiving test results

The comprehensive metabolic panel is a relatively routine test, and laboratories can usually have results available within a few business days after they have received your blood sample.

Your doctor’s office may contact you to describe or discuss your test results. In many cases, you will receive your results in the mail or can access them through an online health portal.

Interpreting test results

A test report for a comprehensive metabolic panel will typically list each of the 14 items measured and what the levels were in your sample. Be aware that several different units are used depending on the specific measurement.

The test report should also list the reference range for each of these 14 items. This is important because not all laboratories use exactly the same methods to measure the components of the CMP. The range of normal results can vary by laboratory, so it is important to consider your test levels in the context of the reference range listed for the lab that analyzed your sample.

To illustrate the potential differences in reference ranges, the following table shows common normal ranges as described by the American Board of Internal Medicine (ABIM) and the National Library of Medicine’s A.D.A.M. Medical Encyclopedia:

Your doctor is in the best position to explain and interpret your CMP test results. The doctor will look to see whether any measurements are abnormally high or low. For abnormal levels, they may consider the degree to which they vary from the laboratory’s reference range.

Interpreting test results often means reviewing each level in the context of the test’s other measurements. Patterns relating to which levels are abnormal can provide meaningful information for the doctor to try to understand the underlying cause of your results. These patterns can help evaluate your kidney and liver condition as well as your metabolic health.

Do I need follow-up tests?

Follow-up tests may be recommended after a comprehensive metabolic panel, but this depends on your test results as well as your health history and current health, including any ongoing symptoms or concerns.

If your test results suggest a possible health problem, such as disrupted liver or kidney function, the doctor may prescribe additional blood or imaging tests to learn more about your situation. In some cases, the CMP may be repeated at a later date to see if your results remain abnormal.

Questions for your doctor about test results

Once you have results back from your CMP, you can discuss what they mean with your doctor, and some of these questions may help you understand the significance of your test report:

• Were any of the measurements on my test abnormal? If so, which ones?
• What might explain any abnormal results?
• Based on my CMP results, are there any other tests that you recommend?
• Should I have the CMP test again? If so, when should it be done?

There is overlap between the comprehensive metabolic panel and other types of lab tests. The following sections provide more information about tests related to the CMP.

How is the comprehensive metabolic panel different from the basic metabolic panel (BMP)?

Both the comprehensive metabolic panel and the basic metabolic panel are blood tests, but, as the names indicate, the CMP involves more measurements than the BMP. The CMP includes 14 components, and the BMP typically has 8. The following table illustrates the parts of the typical BMP and CMP:

As this demonstrates, all of the measurements in the BMP are also in the CMP. However, the CMP adds the tests found in a typical liver panel test.

Other related tests

Each of the components of the CMP can be measured alone or as parts of other types of panel tests. The links below provide more information about each specific measurement included in the CMP:

• Alanine Aminotransferase (ALT)
• Alkaline Phosphatase (ALP)
• Albumin
• Bicarbonate
• Bilirubin
• Blood Urea Nitrogen
• Calcium
• Chloride
• Creatinine
• Glucose Tests
• Potassium
• Sodium
• Total Protein (TP)

The comprehensive metabolic panel is a way to assess various elements of health. The following links provide background information about some of these elements:

• National Institute of Diabetes and Digestive and Kidney Diseases: Liver Disease
• National Institute of Diabetes and Digestive and Kidney Diseases: Kidney Disease
• CDC: Diabetes
• National Library of Medicine: Fluid and Electrolyte Balance

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