The Cardiovascular
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Albumin-corrected calcium

Corrects total serum calcium for hypo- or hyperalbuminaemia.

Albumin-corrected calcium
Measured total calcium
Serum albumin
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When to use

  • Interpreting total serum calcium when albumin is abnormal — the classic setting is hypoalbuminaemia masking true normocalcaemia.

Formula

Corrected calcium (mg/dL) = measured calcium + 0.8 × (4.0 − albumin [g/dL]).

Pearls and pitfalls

  • Ionised calcium is the more reliable measure, particularly in critical illness, acid–base disturbance and renal failure, where correction formulas perform poorly.

References

  1. Payne RB, et al. Interpretation of serum calcium in patients with abnormal serum proteins. BMJ. 1973;4(5893):643–6.