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COMPREHENSIVE METABOLIC PANEL (CMP)
Also printed as: Total calcium · Ca · Serum calcium
Educational only — not medical advice.
Calcium in your blood supports nerve signalling, muscle contraction, and clotting — separate from the much larger amount stored in your bones. Roughly half of it travels bound to albumin, so your albumin level changes what the total number means. Hormones keep the free portion in a very tight band.
Because so much calcium rides on albumin, a total calcium that looks off is often just tracking a protein change. Clinicians routinely "correct" calcium for albumin, or order an ionized calcium, before reading anything into it.
TYPICAL ADULT RANGE
Many labs report roughly 8.6–10.3 mg/dL for adults. Ranges vary by lab, and results are read alongside albumin. Reported in mg/dL.
Reference ranges vary by lab, by method, and by age and sex. Always read your own result against the range printed on your report.
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The most frequent reason for a low total calcium is a low albumin — the free, active calcium is often perfectly fine. Low vitamin D and magnesium can also contribute, as can some medications. If the low persists after accounting for albumin, or comes with tingling or muscle cramps, that is worth raising with your doctor so they can look at vitamin D, magnesium, and parathyroid hormone together.
Mildly high calcium can come from being dehydrated at the draw (which concentrates everything), a tight tourniquet, or high-dose calcium and vitamin D intake. Certain medications, including some diuretics and lithium, raise it as an expected effect. A calcium that stays above range on a repeat is a common reason doctors check parathyroid hormone and vitamin D next — a straightforward follow-up conversation to have with your clinician.
Your doctor is the one who can read this number against your history, symptoms, and medications.
Educational only — not medical advice. Lab results only mean something alongside your history, symptoms, medications, and the rest of your panel. Bring questions to your doctor; they are the one who can interpret your results for you.
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