Studies on blood cholinesterase activity in normal subjects compared with the organophosphate insecticide exposures and patients with some diseases in Thailand

Abstract

Cholinesterase is a group of enzymes that hydrolyzes cholineester especially acetylcholine which is a neurohumoral transmitter of the parasympathetic nervous system. There are two distinct types of cholinesterase, that is: acetylcholinesterase in red blood cells and pseudocholinesterase or serum cholinesterase. In the present study, the red cell and serum cholinesterase levels were determined in 100 Thai blood donors, 58 subjects exposed to organophosphate insecticide, 11 patients with anticholinesterase insecticide poisoning, 35 patients with infectious hepatitis, 57 patients with malarial infection, 30 patients with B/E thalassemia, 8 patients with Hb-H thalassemia, 17 patients with congenital heart disease, 30 pregnant women in the first, second and third trimesters and 24 umbilical cord blood samples. The mean values ± S.D. of serum and red cell cholinesterase levels in Thai blood donors were found to be 3.07 ± 0.71 I.U., 21.28 ± 3.45 I.U. respectively. There was no significant difference (P>0.05) between the mean values of serum and red cell cholinesterase in male and female blood donors. Decreased serum cholinesterase levels were found in people exposed to organophosphate insecticide. There was no significant difference between the mean values of red cell acetylcholinesterase in the exposed group and the normal group. There was no correlation between the duration of working in the factory and serum or red cell cholinesterase levels in directly and non-directly exposures. Patients with acute poisoning of anticholinesterase insecticide had very low serum and red cell cholinesterase activities. Markedly lowered serum cholinesterase activity was found in patients with infectious hepatitis. The recovery of the enzyme were rather quickly, i.e., reaching the normal level within 4-5 weeks. Moderately decreased serum cholinesterase activity was found in patients with falciparum malaria. This low activity of serum cholinesterase in patients with falciparum malaria increased rapidly and reached the normal levels within 4 weeks. Markedly lowered serum cholinesterase activity was found in patients with B/E and Hb-H thalassemia and the red cell cholinesterase activity in patients with B/E thalassemia were found to be higher than that of the normal subjects. There were no significance (P>0.05) difference between the serum and red cell cholinesterase activity in patients with congenital heart disease and the normal subjects. Decreased serum and whole blood cholinesterase activities were found in pregnant women of the first, second and third trimesters. The mean value of serum cholinesterase activity in cord bloods was not significant difference (P>0.05) while mean value of red cell cholinesterase was lower (P<0.0005) than those of the normal values.