Corrected Calcium Calculator
Enter serum calcium and albumin to get albumin-adjusted (corrected) calcium in mg/dL and mmol/L, with instant hypocalcaemia and hypercalcaemia interpretation.
Lab Values
Disclaimer: Estimates only. Albumin-based correction is unreliable in critical illness, acid-base disturbance, dialysis, pancreatitis and pregnancy — measure ionised calcium in those settings and always apply clinical judgement.
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How corrected calcium is calculated
Roughly 40% of circulating calcium is bound to albumin, so a low albumin lowers total calcium without changing the biologically active ionised fraction. The standard adjustment is Corrected calcium = [0.8 × (4.0 − albumin g/dL)] + measured calcium mg/dL. In SI units the equivalent is corrected Ca (mmol/L) = measured Ca + 0.02 × (40 − albumin g/L).
Interpretation ranges (corrected calcium)
- → < 8.5 mg/dL — Hypocalcaemia
- → 8.5–10.5 mg/dL — Normal
- → 10.6–12 mg/dL — Mild hypercalcaemia
- → 12.1–14 mg/dL — Moderate hypercalcaemia
- → > 14 mg/dL — Severe hypercalcaemia (emergency)
Frequently Asked Questions
What is the corrected calcium formula?
Corrected calcium (mg/dL) = [0.8 × (4.0 − patient albumin g/dL)] + measured serum calcium (mg/dL).
What is a normal corrected calcium?
Usually 8.5–10.5 mg/dL (2.12–2.62 mmol/L), with small variation between laboratories.
When should ionised calcium be used instead?
In ICU patients, acid-base disturbance, massive transfusion, dialysis, pancreatitis and pregnancy, where the albumin correction is unreliable.
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Reference: calcium and albumin binding physiology — NCBI StatPearls: Hypercalcemia.