Measurement of serum cholinesterase level in normal Thai people

Serum cholinesterase (ChE) level has been used as an indicator for an exposure to organophosphorus and carbamate insecticides by showing a lower level than normal people. Normality serum ChE level may vary depending on sex, age and occupation. The serum of 568 blood donors at Maharaj-Nakorn Chiang Mai Hospital was collected to study the variation of ChE level among different occupations, sex and age. Enzyme ChE activity was measured using butyrylthiocholine as a substrate and dithiobisnitrobenzoate as a chromophore. The results showed that an average ± SD level of serum ChE in those of blood donors was 6,043 ± 1,247 U/L. There was no significant different in mean serum ChE level between group of monks (n=13), unemployees (n=16), traders (n=25), soldier and policemen (n=102), civil services (n=35), employees (n=195) and students (n=75) at 95% confidence. But in farmers (n=107), the serum ChE level appeared to be lower than in other occupational groups. Furthemore, there was a significant different in serum ChE level between females and males which show mean ± SD ChE activities at 5,421 ± 1,104 U/L (n=65) and 6,123 ± 1,243 U/L (n=503) respectively. However the ChE level in different age groups were not significantly different in this study. 

Children's plasma cholinesterase activity and fatal methomyl poisoning.

There is a case of a couple who intentionally killed their children with methomyl insecticide. This was presented as our initial investigation of plasma cholinesterase (ChE) activity in Thai children. A hundred and five healthy Thai children 5-6 years of age, participated in the project. Their plasma was drawn to measure ChE activity. Mean +/- standard deviation of the children ChE was 7,417 +/- 1,620 U/L. The enzyme activity of the children was not significantly different between gender and parents' occupations. However, the mean of female ChE activity appeared to be lower than male ChE. Children whose parents were farmers appeared to have lower ChE activity than those whose parents were employees, merchants, government officers, unemployed parents, or private business owners. Two victims of child homicide were presented with ChE activity approximately 6 and 9 per cent of the average, considering healthy children. It was concluded that children's plasma ChE activity lower than 10 per cent of normal, could be a lethal indicator of anti-ChE insecticide poisoning.