Development of reference intervals for serum alkaline phosphatase among adults in Southern China traced to the new IFCC reference measurement procedure

Background: Serum alkaline phosphatase (ALP) plays a critical role in the diagnosis of various diseases, and the establishment of relevant, reliable reference intervals (RI) is key to avoiding misdiagnoses. In 2011, IFCC published the new reference measurement procedure (RMP) for the determination of serum ALP in which one of the main modifications was the measuring temperature of the assay. Here, the new RMP was used to help establish RIs for serum ALP concentrations in healthy Chinese Han. Methods: Volunteer individuals in Guangdong province, China (n = 1622) were screened by questionnaire and laboratory testing for eligibility as a reference. Blood (20 mL) was collected and samples were measured by the Roche Modular system using the new RMP for the serum ALP compatible method. Partitioning of values by gender and/or age was evaluated with a standard normal deviate test after removing outliers. A simple non-parametric method for a two-sided 95% distribution of reference values was calculated. Results: Serum ALP concentrations were obtained from the cohort of eligible reference individuals (n = 658). The RI for serum ALP in males age 18-79 years was 48-131 U/L. Females were partitioned into two age groups based on statistical analysis, 18-49 years and 50-79 years, and the RIs derived were 40-106 U/L and 57-159 U/L, respectively. Conclusions: RIs for serum ALP for Chinese Han individuals in between the ages of 18 and 79 years were determined and required partitioning due to the higher ALP values of females age 50-79 years.