Corrected Calcium Calculator

What is Corrected Calcium?

Corrected calcium is a calculated value used by healthcare professionals to estimate the active concentration of calcium in a patient's blood. In the human body, a significant portion of calcium is bound to proteins, primarily albumin. Only the unbound (free or ionized) calcium is biologically active. For related clinical tools, try the Corrected Sodium Calculator and GFR Calculator.

Why Correct Calcium for Albumin?

When a patient has low albumin levels (hypoalbuminemia), the total calcium concentration measured in standard blood tests will appear artificially low, even though the active, ionized calcium level is normal. This calculator uses the standard Payne's formula to correct measured total calcium based on the patient's albumin levels.

The Corrected Calcium Formulas

Depending on the units used for the lab measurements, the calculations are as follows:

Conventional Units (calcium in mg/dL, albumin in g/dL): $$\text{Corrected Calcium} = \text{Measured Calcium (mg/dL)} + 0.8 \times (4.0 - \text{Albumin (g/dL)})$$

SI Units (calcium in mmol/L, albumin in g/L): $$\text{Corrected Calcium} = \text{Measured Calcium (mmol/L)} + 0.02 \times (40.0 - \text{Albumin (g/L)})$$