A comprehensive metabolic panel — usually abbreviated CMP — is one of the most commonly ordered blood tests in routine medicine. From a single blood draw, it generates 14 separate measurements covering kidney function, liver health, blood glucose, electrolytes and acid-base balance.
Because it surveys so many systems at once, the CMP is used both for routine wellness screening and to investigate a wide range of symptoms. Here's what each component measures.
Glucose
Glucose on a CMP is typically a fasting measurement. Normal: below 5.6 mmol/L (100 mg/dL). Elevated fasting glucose is the first indicator of pre-diabetes or diabetes and is reviewed in the context of HbA1c for a fuller picture.
Kidney markers: creatinine, BUN and eGFR
Creatinine is a waste product filtered by the kidneys. BUN (blood urea nitrogen) is another kidney waste marker. eGFR (estimated glomerular filtration rate) is calculated from creatinine alongside age, sex and other factors — it estimates the percentage of normal kidney function remaining.
- **Normal eGFR:** above 90 mL/min/1.73m² (some decline with age is normal)
- **Mild reduction:** 60–89 — monitor and investigate causes
- **Moderate reduction:** 30–59 — kidney disease likely, specialist review warranted
- **Severe:** below 30 — requires nephrology involvement
Liver markers: ALT, AST, ALP and bilirubin
ALT (alanine aminotransferase) and AST (aspartate aminotransferase) are enzymes that leak into the bloodstream when liver cells are damaged. ALT is more liver-specific. ALP (alkaline phosphatase) reflects bile duct function and bone health. Total bilirubin is a breakdown product of haemoglobin; elevated levels cause jaundice.
Isolated mild elevations — particularly ALT up to three times the upper limit of normal — are extremely common and often benign, but persistent elevation warrants investigation.
Protein: total protein and albumin
Total protein and albumin reflect the liver's ability to synthesise protein and the body's overall nutritional state. Low albumin is a sensitive marker of malnutrition, chronic illness and advanced liver or kidney disease.
Electrolytes: sodium, potassium, chloride and CO₂
These four electrolytes regulate fluid balance, nerve signalling, muscle contraction and blood pH. Sodium is the most abundant — low sodium (hyponatraemia) is a common hospital finding with many causes. Potassium is critical for heart and muscle function; both high and low levels can cause cardiac arrhythmias.
The CO₂ (bicarbonate) value reflects acid-base balance. A low reading can indicate metabolic acidosis; a high reading points to alkalosis.
Calcium
Calcium on a CMP is total serum calcium — reflecting bone turnover, parathyroid function and vitamin D status. Mildly elevated calcium (hypercalcaemia) is a common incidental finding, most often caused by primary hyperparathyroidism. Low calcium (hypocalcaemia) causes muscle cramps, tingling and, in severe cases, cardiac problems.
Reading your CMP in context
Because the CMP covers 14 values, statistically one or two will be just outside the reference range in any healthy person on any given day. A single borderline result is far less meaningful than a pattern across several values, or the same value trending in one direction across multiple tests.
Tracking your CMP results over time — comparing this year's creatinine to last year's, or watching whether an elevated ALT resolves — is where the real clinical value lies. Looms organises your lab results chronologically, flags trends and makes it easy to share complete histories with any provider.