Corrected Calcium
Calculator

About 40-45% of calcium in the blood is bound to albumin, so when albumin levels are low, total measured calcium appears artificially low even though the biologically active, unbound (ionized) calcium may be normal. The correction formula estimates what the total calcium would be if albumin were at a normal level.

A common formula adds 0.8 mg/dL to the measured total calcium for every 1 g/dL that albumin falls below a normal reference value (usually 4.0 g/dL). This adjustment compensates for the reduced calcium-binding capacity caused by low albumin.

It's particularly relevant for patients with low albumin due to malnutrition, liver disease, chronic illness, or critical illness, where relying on uncorrected total calcium could lead to a missed diagnosis of true hypercalcemia or an incorrect diagnosis of hypocalcemia. In these patients, uncorrected values can be significantly misleading.

No, directly measured ionized calcium is considered the gold standard and is more accurate than the albumin-corrected estimate, especially in critically ill patients or those with acid-base disturbances that also affect calcium binding. The corrected calcium formula is a useful estimate when ionized calcium testing isn't readily available.

No, corrected calcium values should always be interpreted by a healthcare provider alongside symptoms, other lab results, and clinical context. This tool is meant for reference and educational understanding, not for guiding treatment on its own.