Comparison of two methods measuring serum alkaline phosphatase in neonates.

Abstract

Serum alkaline phosphatase (ALP) is a useful bone turnover marker to diagnose metabolic bone disease in preterm infants. In Japan, serum ALP levels were generally measured using the Japan Society of Clinical Chemistry (JSCC) method. It is problematic that ALP levels measured using the JSCC method tend to be higher in people with blood types B and O regardless of the disease. For international standardization, since 2020, the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) method has been used as a reference method for ALP measurement instead of the JSCC method. However, no report has investigated the correlation between these two methods in neonates. We therefore aimed to compare the JSCC and IFCC methods and demonstrate a conversion formula in neonates. In this retrospective study, we used a total of 402 samples in 49 preterm and 38 term infants. Serum ALP levels were measured using the JSCC and IFCC methods. Alkaline phosphatase measured using the JSCC method strongly correlated with that measured using the IFCC method in all blood types in preterm and term infants (P < 0.01 for all). We found that the serum ALP levels measured using the IFCC method could be calculated as 0.34 times the ALP levels measured using the JSCC method in preterm and term infants with any blood type: ALP levels (IFCC method) = 0.34 × ALP levels (JSCC method).