The 14 markers in a CMP
| Marker | What it reflects | Guide |
|---|---|---|
| Glucose | Blood sugar at the moment of the draw | Fasting glucose |
| Calcium | Mineral for nerves, muscles and heart; mostly stored in bone | Calcium |
| Sodium | Electrolyte for fluid and pH balance | Sodium |
| Potassium | Electrolyte for fluid, acid-base balance and heart rhythm | Potassium |
| Bicarbonate (CO2) | Electrolyte for acid-base balance | CO2 |
| Chloride | Electrolyte for fluid and acid-base balance | Chloride |
| Albumin | Main blood protein, made by the liver | Albumin |
| Total protein | Albumin plus globulins | Globulin |
| ALP | Enzyme from the liver and bone | Alkaline phosphatase |
| ALT | Liver enzyme | ALT |
| AST | Liver enzyme, also found in muscle | AST |
| Bilirubin | Waste from broken-down red cells, cleared by the liver | Bilirubin |
| BUN | Waste product filtered by the kidneys | BUN |
| Creatinine | Waste product filtered by the kidneys | Creatinine |
CMP vs BMP
A basic metabolic panel (BMP) has 8 of the 14 tests: glucose, calcium, sodium, potassium, CO2, chloride, BUN and creatinine. It leaves out total protein, albumin, bilirubin and the liver enzymes ALP, ALT and AST. Your clinician picks one based on what they need to check.
Calculated results such as eGFR and the anion gap come from these same numbers. For more detail, see the CMP lab guide.
Do you need to fast?
Often, yes. MedlinePlus says you may need to fast for several hours before a CMP, and about eight hours before a BMP. Fasting mostly matters for the glucose result. Follow the instructions from your clinician or lab, and ask before skipping any medicine.
What abnormal results can mean
Patterns matter more than any single number:
- High glucose can be a sign of diabetes, especially if fasting. An A1C test shows the longer-term average.
- Abnormal electrolytes (sodium, potassium, chloride, CO2) can reflect dehydration or fluid losses, kidney, heart or liver disease, acid-base problems, diabetes or medicines such as diuretics and steroids.
- High BUN can mean the kidneys aren't working well, but also dehydration, a high-protein diet or certain medicines. Creatinine helps tell these apart.
- Abnormal ALT, AST, ALP or bilirubin can point to liver inflammation or bile duct problems. High ALP can also come from bone.
- Albumin and total protein are mostly made in the liver, so they are read alongside the liver tests.
Results just outside the range are common and often normal for you. Your clinician may repeat the test or add follow-up tests before drawing conclusions.
Seek care promptly if an abnormal CMP comes with confusion, severe weakness, an irregular heartbeat, yellowing skin or eyes, very little urine, or severe belly pain.
Common questions
What does a CMP test for?
Blood sugar, electrolytes and fluid balance, kidney function, liver function and blood proteins, using 14 measurements from one blood draw.
Do you have to fast for a CMP?
You may be asked to fast for several hours, mostly so the glucose result is accurate. Follow your lab's instructions.
What is the difference between a CMP and a BMP?
A BMP has 8 of the CMP's 14 tests. It skips total protein, albumin, bilirubin and the liver enzymes ALP, ALT and AST.
Is a CMP the same as a CBC?
No. A CMP checks chemistry such as glucose, electrolytes, kidneys and liver. A CBC counts your blood cells. They are often ordered together.
What if one CMP value is slightly off?
It is common and often not meaningful by itself. Your clinician looks at the pattern, your medicines and your history, and may repeat the test.
Sources
- Comprehensive Metabolic Panel (CMP) MedlinePlus, U.S. National Library of Medicine
- Basic Metabolic Panel (BMP) MedlinePlus, U.S. National Library of Medicine
- Liver Function Tests MedlinePlus, U.S. National Library of Medicine
- Electrolyte Panel MedlinePlus, U.S. National Library of Medicine
- BUN (Blood Urea Nitrogen) MedlinePlus, U.S. National Library of Medicine
- Diabetes Testing Centers for Disease Control and Prevention (CDC)
This guide is general information, not medical advice. It does not replace a visit with a licensed clinician. Gabriel membership is not health insurance.