CMP blood test: how to read your comprehensive metabolic panel

A CMP (comprehensive metabolic panel) is one of the most common blood tests in the US. It measures 14 substances in one tube: blood sugar, kidney markers, electrolytes, calcium, proteins and liver tests. It is often part of a yearly physical. A result marked H or L only means the number is outside your lab's range; with 14 lines, one slightly off value is common and often means little on its own.

Updated: 2026-11-04

Reference ranges

Category	Reference range
Glucose	70–100 mg/dL (fasting) typical adult ranges (US units)
BUN (blood urea nitrogen)	6–20 mg/dL typical adult ranges (US units)
Creatinine	0.6–1.3 mg/dL typical adult ranges (US units)
Sodium	135–145 mEq/L typical adult ranges (US units)
Potassium	3.7–5.2 mEq/L typical adult ranges (US units)
Chloride	96–106 mEq/L typical adult ranges (US units)
CO2 (carbon dioxide, bicarbonate)	23–29 mEq/L typical adult ranges (US units)
Calcium	8.5–10.2 mg/dL typical adult ranges (US units)
Total protein	6.0–8.3 g/dL typical adult ranges (US units)
Albumin	3.4–5.4 g/dL typical adult ranges (US units)
Total bilirubin	0.1–1.2 mg/dL typical adult ranges (US units)
ALP (alkaline phosphatase)	20–130 U/L typical adult ranges (US units)
ALT	4–36 U/L typical adult ranges (US units)
AST	8–33 U/L typical adult ranges (US units)

Example ranges from MedlinePlus. Every lab sets its own reference ranges, and they differ by method, age and sex: always compare with the range printed next to your result.

What a CMP blood test checks

The CMP is a snapshot of your body chemistry. It is ordered at routine checkups, to look for the cause of symptoms such as tiredness or swelling, and to monitor conditions or medicines that can affect the kidneys or liver. Blood is drawn from a vein in your arm. Many offices ask you to fast for 8 to 12 hours, mainly because of glucose; follow what you were told when the test was ordered.

A BMP (basic metabolic panel) is the same test minus six lines: it keeps glucose, BUN, creatinine, sodium, potassium, chloride, CO2 and calcium, and leaves out total protein, albumin, bilirubin, ALP, ALT and AST. If your report says BMP, the liver section below does not apply.

Sugar and kidneys: glucose, BUN, creatinine

Glucose: blood sugar at the moment of the draw. Fasting, 100–125 mg/dL is the prediabetes range and 126 or more needs confirmation. If you were not fasting, a higher value is expected. More in fasting glucose.
BUN: a waste product from protein breakdown, cleared by the kidneys. It rises with dehydration, a high-protein diet or some medicines, not only with kidney problems.
Creatinine: the main kidney marker, also tied to muscle mass. See high creatinine.
eGFR: not one of the 14 tests, but most US reports print it right under creatinine. It is calculated from creatinine, age and sex and estimates how well the kidneys filter. See low eGFR.

Electrolytes and calcium

Sodium and chloride reflect water balance. Mild changes are common with dehydration, vomiting, diarrhea or some blood pressure medicines.
Potassium matters for heart rhythm. A slightly high value is sometimes an artifact: if the sample sat too long or the cells broke during the draw (hemolysis), potassium leaks out of them. Labs often note this, and the test is simply repeated.
CO2 (bicarbonate) shows the acid-base balance of the blood; it can shift with breathing problems, kidney disease or long bouts of vomiting.
Calcium depends on albumin, because part of it travels bound to that protein. A low calcium with a low albumin is often not a real calcium problem.

Proteins and liver tests

Total protein and albumin: albumin is made by the liver; low values can relate to liver or kidney disease or poor nutrition, high values usually to dehydration.
ALT and AST: liver enzymes. Mild rises are common after hard exercise, alcohol, some medicines or with fatty liver. See elevated liver enzymes.
ALP: comes from the liver and bones; it is normally higher in teenagers who are still growing and in pregnancy.
Total bilirubin: a breakdown product of red cells. A mildly high value with otherwise normal liver tests is often harmless (Gilbert syndrome is common). If the report also gives direct bilirubin, see direct bilirubin high.

How to read flagged CMP results

Read the panel in groups rather than line by line: sugar, kidneys (creatinine with BUN and eGFR), electrolytes, liver (ALT, AST, ALP, bilirubin). One line slightly outside the range with the rest of its group normal is often not significant; several abnormal lines in the same group deserve more attention. Compare with your previous results if you have them: a stable number matters less than a clear change.

Results usually arrive within one to two business days and often appear in your patient portal before your doctor has commented. That is normal. The final interpretation is made by the doctor who ordered the test, together with your history and medicines. For general tips on reading a report, see how to read blood test results.

When to see a doctor

Ask your doctor about any flagged result at your follow-up. Contact them sooner if glucose is 126 mg/dL or more fasting, if creatinine is high or eGFR has dropped, if several liver tests are abnormal at once, or if potassium or sodium are well outside the range. Call 911 in the US or Canada (999 in the UK) if you have chest pain, an irregular or very slow heartbeat, severe weakness, confusion, yellow skin or eyes with abdominal pain, or you stop passing urine.

Sources

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Frequently asked questions

What does a CMP blood test check for?

Blood sugar, kidney function (BUN, creatinine), electrolytes (sodium, potassium, chloride, CO2), calcium, proteins (total protein, albumin) and liver tests (ALT, AST, ALP, bilirubin): 14 results in all.

Do I need to fast for a CMP?

Often yes, for 8 to 12 hours, mainly so the glucose result can be read as fasting. Water is fine. Follow the instructions you were given when the test was ordered.

What is the difference between a CMP and a BMP?

A BMP has 8 tests: glucose, BUN, creatinine, sodium, potassium, chloride, CO2 and calcium. A CMP adds total protein, albumin, bilirubin, ALP, ALT and AST.

Does a CMP include cholesterol or a blood count?

No. Cholesterol is a separate lipid panel, and red and white cells are counted in a CBC. They are often drawn at the same visit, so they may appear on the same report.

One CMP result is flagged high. Should I worry?

Usually not on its own. A single line slightly outside the range, with the rest of its group normal, is common. Your doctor will look at the whole panel and may simply repeat it.

This material is for general information only. It is not a medical opinion and does not replace a consultation with a doctor. Reference ranges depend on the laboratory and the method — rely on the range printed on your own report. Your doctor makes the final interpretation.