Biochemistry
Albumin-corrected calcium calculator (Payne formula)
Correct total serum calcium for hypoalbuminaemia using the Payne formula, in either conventional or SI units. For use by licensed clinicians.
Units
Albumin-corrected calcium
9.20mg/dL
The Payne correction is an approximation and performs poorly in critical illness, renal failure and marked acid–base disturbance. Where the result changes management, measure ionised calcium rather than correcting a total.
For use by licensed clinicians as a calculation aid only. It does not account for the individual patient context, and it does not replace clinical judgement or your local protocol. Verify any value before it informs a dose or a decision.
Equation used
Corrected Ca (mg/dL) = measured Ca + 0.8 × (4.0 − albumin g/dL). In SI units: corrected Ca (mmol/L) = measured Ca + 0.02 × (40 − albumin g/L).
Source
Payne RB et al., British Medical Journal, 1973
An approximation derived in a general hospital population. It performs poorly in critical illness, renal failure and marked acid–base disturbance.
Common questions
When should ionised calcium be measured instead of corrected?
Whenever the result would change management, and specifically in critical illness, renal failure, acid–base disturbance, massive transfusion and pancreatitis. Ionised calcium is the physiologically active fraction and the correction is only an estimate of it.
Does acidosis affect the correction?
Yes. Acidosis increases the ionised fraction for a given total calcium and alkalosis decreases it, and the Payne formula does not account for pH at all. In a significant acid–base disturbance, measure ionised calcium.