Roughly 40% of calcium is albumin-bound; a low albumin reads as a falsely low total calcium. Ionised calcium on a blood gas is the true answer when it matters.
What you enter
Total calcium (mmol/L or mg/dL)
Albumin (g/L or g/dL)
FORMULACorrected Ca (mmol/L) = measured Ca + 0.02 × (40 − albumin g/L) [mg/dL: Ca + 0.8 × (4 − albumin g/dL)]
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