[The Study of a New Formula for Correcting Serum Calcium Levels, Considering the Difference in Albumin Analysis...

In Japan, Payne's formula [corrected Ca=total Ca+ (4-ALB)] has been used to correct serum calcium concentration levels. However, the current methods for measuring calcium and albumin differ from those that were used to establish the Payne's formula. For albumin measurement, particularly, values differ be- tween BCG and improved BCP method. In 2014, Ohba et al. reported a modified formula [corrected Ca= total Ca+0.7X (4-ALB)], which is more suitable for correcting calcium with the improved BCP method than with the Payne's method. In the same year, the recommendation for converting albumin concentration with the improved BCP method to that with the BCG method was presented by the Japanese Society of La- boratory Medicine. Thus, we conceived a new modified formula [corrected Ca=total Ca+ {4- (BCP+ 0.3) }], which is included in the contents of this recommendation, and examined the effects of this formula in comparison with the Payne and Ohba methods. The patients recruited for the calcium adjustment were as follows: (i) all patients; (ii) patients with albumin concentrations <4.0 g/dL; and (iii) patients with albumin concentrations ≤3.5 g/dL. Payne's formula overcorrected calcium with the improved BCP method. Ohba's method was suitable for (i), while the new for- mula was specifically more suitable for (iii) than the Payne and Ohba formulas. The present study showed that our new formula is more suitable for calcium adjustment in patients with albumin concentrations ≤3.5 g/dL. [Original].