The Worth of Total Calcium Levels Adjusted By Various Formulae in the Di-agnosis of Hypocalcemia

Abstract

Purpose: The aim was to evaluate the diagnostic accuracy of the corrected total calcium (cCa) calculated with different formulas in the diagnosis of hypocalcemia. Materials and Methods: Whole blood free calcium and serum total calcium levels of a total of 410 individuals were evaluated.cCa levels were calculated using the Modified Orrell, Orrell, Payne, Berry, and James methods. In each of the hypoalbuminemia and normoalbuminemia groups, the diagnostic performance parameters of measured total calcium and cCa in the diagnosis of hypocalcemia were calculated. Hypocalcemia was diagnosed by measuring free calcium levels. The difference between the groups was analyzed using the Mann-Whitney.U test.A Spearman correlation analysis was performed to determine the correlation between free calcium and total Ca levels. Results: In the diagnosis of hypocalcemia, the test with the highest sensitivity in the hypoalbuminemia group was the total calcium test, measured at a rate of 80.3%. The sensitivity was <60% in all cCa levels calculated with the five different formulas. Sensitivity rates were <40% for measured and all cCa concentrations in the normoalbuminemia group.In the hypoalbuminemia group, a low level of correlation was observed between free calcium and each calcium level calculated by the Modified Orrell, Payne, Orrell, Berry, and James method (p<0.001,r=0.240;0.258;0.230;0.247;0.193). Conclusion: The formulas used to calculate the cCa concentration need improvement. cCa did not replace free calcium,and cCa did not outperform the total calcium level in the diagnosis of hypocalcemia.We are of the opinion that it is not reliable to comment on the free calcium levels by cCa concentration.

Keywords

• corrected calcium
• free calcium
• hypocalcemia
• diagnostic performance