Factors affecting biological variation in total cholinesterase activity in plasma were studied in a population of 3372 apparently healthy subjects at least four years old. Determination of the dibucaine number, after inhibition of the activity by dibucaine, made it possible to specify the contributions of genetic and physiological characteristics to variations in the total activities by using a statistical method of segmentation. The main factors modifying plasma cholinesterase activity in males are genetic status (dibucaine number) and degree of overweight (subscapular skinfold). In females, hormonal status (puberty or menopause), genetic status (dibucaine number), and the use of oral contraceptives are the factors mainly responsible for the variations of plasma cholinesterase activity. These data allow us to propose reference limits for total plasma cholinesterase.
PIP: This study demonstrated the relative effects of sources of biologic variation in total cholinesterase activity in plasma in 3372 healthy subjects. Determination of the dibucaine number, after inhibition of the activity by dibucaine, made it possible to specify the contributions of genetic and physiologic characteristics to variations in the total activities by using a statistical method of segmentation. The main factors modifying plasma cholinesterase activity in males are genetic status (dibucaine number) and degree of overweight (subscapular skinfold); in females, the most important factors are hormonal status (puberty or menopause), genetic status (dibucaine number), and the use of oral contraceptives. These data facilitate the definition of reference limits for total plasma cholinesterase. In this study, the reference sample consisted of 1973 individuals--55% of all the males and 50% of all the females. In this reference group, activity levels were higher in males than in females. This is 1 of the few studies to evaluate both genetic and environmental influences on cholinesterase activity in the same population.