Sources of variation analysis and derivation of reference intervals for ALP, LDH, and amylase isozymes using sera from the Asian multicenter study on reference values

Abstract

Background: Sources of variation (SV) of ALP, LDH, and amylase isozymes were explored.

Methods: We analyzed 3511 sera from well-defined healthy individuals recruited during the 2009 Asian project for derivation of common reference intervals (RIs). Up-to-date electrophoresis auto-analyzer and reagents were employed for high resolution and reproducibility. SVs including sex, age, body mass index (BMI), ABO blood groups, and levels of drinking, smoking, and exercise were analyzed by multiple regression analysis. RIs were determined by parametric methods after refining healthy individuals by use of latent reference values exclusion method.

Results: Age-related changes in ALP2-3 were different in females: ALP2, linear increase from 20-64y; ALP3, lowering until 45 y and rising steeply thereafter. ALP2 increased with BMI especially in females. ALP5 was barely detectable except in blood-types O and B. Age-related increases in LDH1-LDH3 were noted in females, whereas BMI-related increases were found only for LDH2-LDH5 in both sexes. Pancreatic amylase showed age-related increase in females and was slightly higher in blood-type O. RIs for absolute and relative activities of each isozyme were derived in consideration of sex and age.

Conclusions: Investigation of these isozymes revealed various age-, BMI-, and blood-type-related changes that are all relevant in clinical interpretation of enzyme test results.

Keywords: ABO blood group; ANOVA; Age-related change; Multiple regression analysis; Regionality.