What does a CMP measure?
Those 14 results are easier to understand when you group them by what they help your provider assess.
Blood sugar: glucose
Glucose is a sugar your body uses for energy. Your CMP shows how much glucose was in your blood at the time of the draw, so whether you were fasting matters when interpreting that number.
Glucose is different from hemoglobin A1c, which reflects your average blood sugar over roughly three months, as explained by the
National Institute of Diabetes and Digestive and Kidney Diseases.
The CMP also doesn't measure insulin. Our article,
Understanding Your Blood Work: Fasting Insulin Test, covers that separate measurement and why it can reveal blood sugar concerns earlier.
Your provider can help decide which tests make sense for you.
Kidney health: BUN and creatinine
Blood urea nitrogen (BUN) measures nitrogen from urea, a waste product formed when your body breaks down protein. Creatinine is a waste product of normal muscle activity. Your kidneys filter both out of your blood.
These results help your provider assess how well your kidneys are working.
Your report may also list an estimated glomerular filtration rate (eGFR). It is calculated from creatinine and other information, so it's an estimate of kidney filtration rather than a separately measured substance.
The National Kidney Foundation's
guide to reading a CMP explains these markers in more detail.
Fluid and acid-base balance: sodium, potassium, chloride, and carbon dioxide
These four electrolytes support nerve signaling, muscle movement, and healthy fluid balance.
The carbon dioxide result, often labeled CO2, mostly reflects bicarbonate in your blood. Bicarbonate helps keep your blood from becoming too acidic or too alkaline.
Because your kidneys help regulate electrolytes, your provider may review these numbers alongside BUN and creatinine. Things like dehydration, vomiting or diarrhea, and certain medications can also affect electrolyte results.
Calcium and proteins: calcium, albumin, and total protein
Calcium supports muscle and nerve function as well as bone health. A CMP measures total calcium, which includes calcium bound to proteins and calcium circulating freely.
Albumin is a protein made by your liver. Total protein measures albumin plus another group of proteins called globulins. These proteins transport substances through your body and support immune function.
Protein results can point to several conditions, but they aren't a measure of how much protein you eat.
This group shows why results belong together. Much of the calcium in your blood is attached to albumin, so a change in albumin can shift total calcium even when free calcium stays the same.
When a closer look is needed, your provider may order an ionized calcium test. MedlinePlus explains the difference in its
guide to calcium blood tests.
Liver-related measurements: ALP, ALT, AST, and bilirubin
Alkaline phosphatase (ALP), alanine aminotransferase (ALT), and aspartate aminotransferase (AST) are enzymes. Changes in their levels can help your provider look into liver or bile duct concerns.
Not all of them are specific to the liver, though: AST is also found in muscle, and ALP is found in bone and other tissues.
Bilirubin forms during the normal breakdown of red blood cells. Your liver processes it so your body can remove it.
Your provider looks at the pattern across these results, sometimes alongside albumin and other liver tests. One elevated enzyme on its own doesn't identify a cause or confirm a diagnosis.
