Calculators · Endocrinology · Formula

Albumin-adjusted (corrected) calcium — Payne

Also called corrected calcium, adjusted calcium

Adjusts total serum calcium for a low or high albumin, as published by Payne et al. (1973).

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Formula and scoring

Adjusted Ca (mg/dL) = measured Ca (mg/dL) − albumin (g/dL) + 4.0 (Payne 1973).

Exam and ward pearls

  • Payne's published formula uses a slope of 1.0 mg/dL per g/dL; many textbooks quote 0.8 mg/dL per g/dL instead. This calculator uses the published 1.0.
  • Hyper-gammaglobulinaemia raised total protein but not calcium in Payne's series, which is why albumin, not total protein, is used.

When not to rely on it

  • Derived from 200 specimens sent for liver function tests in one laboratory; ionised calcium is the direct measurement.

Source

  1. Payne RB, Little AJ, Williams RB, Milner JR. Interpretation of serum calcium in patients with abnormal serum proteins. Br Med J. 1973;4(5893):643-6. doi:10.1136/bmj.4.5893.643 · PMID 4758544

Formula and cut-offs checked against these sources on 8 Nov 2026. Educational tool for clinicians; it does not replace clinical judgement.

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