Factors affecting inter-individual variation in human plasma cholinesterase activity: Body weight, height, sex, genetic polymorphism and age

Abstract

The influence of body weight, height, age and sex on plasma cholinesterase activity (ChE) in 650 males and 437 females with ChE-1 phenotype U (genotype ChE^uChE^u or ChE^uChE^s) or UA (genotype ChE^uChE^a) was studied in a multiple regression model. ChE was not influenced by age (p > 0.01), but, like other liver synthesized plasma enzymes, highly (p < 0.001) influenced by body weight and height. In a logarithmic scale ChE followed a linear model (R=0.535, p < 0.001) with randomly distributed residuals, lnChE= 3.286 −0.308 x ChE-1 phenotype −0.104 x sex + 0.00765 x weight −0.00723 x height (U=1, UA=2; male=1, female =2; kg; cm). A simplified model based on body-mass index (BMI = weight divided by squared height, kg/m²), lnCHE=2.016−0.308× ChE-1 phenotype −0.091 x sex + 0.0230 X BMI, showed the same goodness-of-fit (R=0.533). In a non-logarithmic scale both multiple regression models failed to fit cases with high ChE activity. A model for a ‘standardized’ plasma ChE in which the effects of ChE-1 phenotype, sex, body weight and height are eliminated, is proposed to compare ChE in unmatched population groups when using this enzyme activity as a biomarker in environmental or occupational medicine.