About the Test
Purpose of the test
The purpose of the CMP 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 the following reasons:
- 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 checkup to look for indications of underlying issues.
- Monitoring is the process of evaluating 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 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:
- Alanine aminotransferase: (ALT) is an enzyme primarily found in the liver.
- 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.
- Alkaline phosphatase: (ALP) is an enzyme found in tissues throughout the body. It supports numerous biological processes and is most concentrated in the liver and bones.
- Aspartate aminotransferase:(AST) is an enzyme present in the liver and other tissues of the body.
- Bicarbonate: is an electrolyte that reflects the level of carbon dioxide (CO2) in your blood.
- 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.
- Blood urea nitrogen :(BUN) is a measurement of urea nitrogen, a waste material that the kidneys help eliminate from the blood.
- Calcium: is a critical mineral that enables bone health, the functioning of muscles, and the cardiovascular and nervous systems. The main sources of calcium are dietary, but the mineral’s levels in the blood do not normally fluctuate based on diet. Instead, calcium in the blood is usually drawn from being stored in the bones.
- Chloride: is another electrolyte that functions along with sodium, potassium, and bicarbonate to enable a wide range of processes in the body.
- Creatinine: is a by-product of normal muscle activity, a waste product normally filtered and removed from the blood by the kidneys.
- 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.
- Potassium: is an electrolyte present in all tissues of the body and that comes from the foods you eat.
- Sodium: is a type of compound known as an electrolyte; these minerals 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.
- Total protein: is a measurement of the sum of albumin and globulins, which are proteins related to blood vessels and immune function.
When should I get a CMP?
The CMP may be appropriate in a range of different circumstances.
For diagnostic purposes, it may be prescribed when you have symptoms connected to your:
- Kidney
- Liver
- Metabolism
It may also be helpful when you have a general symptom, such as fatigue, that can be caused by many different health conditions.
As a monitoring tool, a CMP may be prescribed if you had a prior abnormal test and the doctor wants to check if your levels remain abnormal.
A CMP can also be used after a treatment has been started to see how your blood levels have changed. For example, if you are starting a new medication that can alter kidney or liver function, the CMP may be a useful tool for making sure these organs are still working properly.
There are no clear guidelines for when the CMP should be used for screening in people without any symptoms or as an essential health screening. While many doctors prescribe the test as part of routine checkups, there is a lack of evidence showing that the benefits of such testing outweigh the risks, such as unnecessary costs and procedures.
Finding a CMP
How can I get a CMP test?
The CMP 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?
No, this test is almost always conducted by obtaining a sample in a lab or other medical setting.
The full CMP is not available as an at-home test kit, though you can order a CMP online and take your form to a lab for sample collection. But 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 to mail to a laboratory where it can be analyzed.
How much does the test cost?
There is not a set price for the CMP. 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 analysis fees, and any office visits. If your insurance plan won’t cover the test, you can use your FSA or HSA to pay for testing.
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.
Taking a CMP
A blood sample is needed for the CMP. 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, 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 to eat after your blood has been drawn. After the test is over, you can drive and return to most normal activities, though you’ll need to wait at least an hour after the draw to exercise or carry heavy objects.
CMP Results
Receiving test results
The CMP 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 CMP 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 essential 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:
| MEASUREMENT | NATIONAL LIBRARY OF MEDICINE’S A.D.A.M. MEDICAL ENCYCLOPEDIA REFERENCE RANGE | ABIM REFERENCE RANGE |
|---|---|---|
| Alanine Aminotransferase (ALT) | 4 to 36 U/L | 10 to 40 U/L |
| Albumin | 3.4 to 5.4 g/dL | 3.5 to 5.5 g/dL |
| Alkaline Phosphatase (ALP) | 20 to 130 U/L | 30 to 120 U/L |
| Aspartate Aminotransferase (AST) | 8 to 33 U/L | 10 to 40 U/L |
| Bicarbonate | 23 to 29 mEq/L | 23 to 28 mEq/L |
| Bilirubin | 0.1 to 1.2 mg/dL | 0.3 to 1.0 mg/dL |
| Blood Urea Nitrogen (BUN) | 6 to 20 mg/dL | 8 to 20 mg/dL |
| Calcium | 8.5 to 10.2 mg/dL | 8.6 to 10.2 mg/dL |
| Chloride | 96 to 106 mEq/L | 98 to 106 mEq/L |
| Creatinine | 0.6 to 1.3 mg/dL | Female: 0.5 to 1.10 mg/dL; Male: 0.7 to 1.30 mg/dL |
| Glucose | 70 to 100 mg/dL | 70 to 99 mg/dL |
| Potassium | 3.7 to 5.2 mEq/L | 3.5 to 5.0 mEq/L |
| Sodium | 135 to 145 mEq/L | 136 to 145 mEq/L |
| Total Protein | 6.0 to 8.3 g/dL | 5.5 to 9.0 g/dL |
Your health care provider is in the best position to explain and interpret your CMP test results. The doctor will check 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.
You may want to ask your doctor some follow-up questions, such as:
- 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?
How is the CMP different from the basic metabolic panel (BMP)?
Both the CMP and the BMP are blood tests, but, as the names indicate, the CMP involves more measurements. The CMP includes 14 components, and the BMP typically has eight. The following table illustrates the parts of the typical BMP and CMP:
| MEASUREMENT | BMP | CMP |
|---|---|---|
| Glucose | ✔ | ✔ |
| Calcium | ✔ | ✔ |
| Sodium | ✔ | ✔ |
| Potassium | ✔ | ✔ |
| Bicarbonate | ✔ | ✔ |
| Chloride | ✔ | ✔ |
| Blood Urea Nitrogen (BUN) | ✔ | ✔ |
| Creatinine | ✔ | ✔ |
| Albumin | ✔ | |
| Total Protein | ✔ | |
| Alkaline Phosphatase (ALP) | ✔ | |
| Alanine Aminotransferase (ALT) | ✔ | |
| Aspartate Aminotransferase (AST) | ✔ | |
| Bilirubin | ✔ |
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.
