Corrected Calcium for Albumin
Corrected Calcium for Albumin - a deterministic tool in Sophie Well's Clinical Math & Conversions group.
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What this is
Estimate albumin-corrected serum calcium with Payne's formula: corrected Ca = measured Ca + 0.8 x (4.0 - albumin g/dL). Sophie Well returns the corrected value and flags hypo- or hypercalcemia against the conventional reference range. Source: Payne RB et al, BMJ 1973.
When to use it
Use this when albumin is abnormal (hypoalbuminemia under-reports total calcium even when the ionized fraction is normal) and an ionized calcium is not immediately available. Albumin correction is a screening estimate, not a substitute for ionized calcium in critical illness, acid-base derangement, or paraproteinemia - in those settings, draw the ionized value.
References
Payne RB, et al. Interpretation of serum calcium in patients with abnormal serum proteins. BMJ. 1973;4(5893):643-646.
Worked example: Corrected Ca 9.6 mg/dL
Sophie Well is a reference and educational tool. Not medical, legal, or financial advice. Does not replace clinician judgment, professional billing review, or legal counsel.