Corrected Calcium for Hypoalbuminemia

Corrected calcium is a calculation used to adjust serum calcium levels in patients with hypoalbuminemia, a condition in which there is a low concentration of albumin protein in the blood. Albumin is a major protein in the blood and is responsible for transporting calcium and other substances. When albumin levels are low, the amount of calcium bound to albumin decreases, leading to a lower total serum calcium level. However, the ionized fraction of calcium, which is biologically active, remains constant. Therefore, it is important to correct the total serum calcium level to reflect the ionized calcium concentration in patients with hypoalbuminemia.

The corrected calcium formula was first described by Payne and subsequently validated by others. The formula is as follows:

Corrected Calcium = Serum Calcium + 0.8 x (4 - Serum Albumin)

Where serum calcium is in mg/dL and serum albumin is in g/dL.

Several studies have demonstrated the importance of using corrected calcium levels in clinical practice, particularly in critically ill patients with hypoalbuminemia. Corrected calcium levels have been shown to be a better predictor of clinical outcomes, such as mortality and length of hospital stay, than total serum calcium levels alone. Furthermore, studies have demonstrated that the use of corrected calcium levels can improve the accuracy of calcium replacement therapy in patients with hypocalcemia.

Corrected calcium is a valuable calculation in the management of patients with hypoalbuminemia. It allows for the correction of total serum calcium levels to reflect the biologically active ionized calcium concentration, which is important for accurate diagnosis and management of calcium disorders.

Healthcare providers should be aware of the corrected calcium formula and its clinical implications in order to provide optimal care to their patients.

References:

• Payne RB. Renal tubular reabsorption of calcium and phosphate derived from the serum ultrafilterable calcium and inorganic phosphate concentrations. Clin Sci 1967; 32: 305-317.