Correlation between the severity of symptoms in organophosphorus poisoning and cholinesterase activity (RBC and plasma) in humans.

This study was undertaken to examine the correlation, if any, between the inhibition of red blood cell cholinesterase (RBC ChE), plasma cholinesterase (PChE) and cerebrospinal fluid acetyl cholinesterase (CSF AChe) and the severity of symptoms in patients poisoned with organophosphorus (OP) compounds. Baseline values of the cholinesterases (RBC, Plasma & CSF) were established in our laboratory using a modified colorimetric method. OP poisoned patients were divided into 3 groups - mild, moderate and severe based on clinical symptoms. We observed a severity dependent inhibition of both RBC ChE and PChE, in acute poisoning. Sequential post exposure estimations of the ChEs upto 5 days not reveal any rise in the values though there was substantial clinical improvement. Our findings therefore indicate that the correlation of ChE values with severity of symptoms are applicable only in the initial stages of acute poisoning. AChE could not be detected in CSF in two severely neurotoxic patients who subsequently expired. The clinical significance of this observation needs to be examined further.