Assessment of Serum Paraoxonase 1 Activity in Patients with Organophosphate Poisoning

Background: Human serum paraoxonase 1 (PON1) hydrolyzes organophosphate (OP) compounds and so significantly alters an individual’s susceptibility to the toxicity of these chemicals. The study was designed to assess the serum PON1 activity in a series of patients with OP poisoning. Methods: Suspected OP poisoning patients presented within 6 hours of consumption at emergency department were recruited. Demographic information of patients, clinical findings, treatments given, complications, length of hospital stay and clinical outcome were collected into datasheets. Patients were graded into moderate and severe poisoning. Serum PON1 was measured by ELISA method and serum cholinesterase by butyrylthiocholine method. Results: Mean serum PON1 level in patients with severe poisoning was significantly lower than those with moderate poisoning (426 ± 179 U/L vs. 868 ± 79 U/L, P < 0.001). Serum PON1 significantly correlated with serum cholinesterase levels (r = 0.400, P < 0.001) and negatively associated with total length of hospital stay (r = -0.338, P < 0.001), total atropine dose (r = -0.826, P < 0.001), serum amylase (r = -0.331, P < 0.001), lipase (r = 0.260, P = 0.011) and total creatinine kinase (r = -0.456, P < 0.001). Serum PON1 and cholinesterase levels were significantly lower in expired patients and those who required ventilation assistance as compared to recovered patients who did not require ventilation assistance. Conclusion: Lower PON1 activity was significantly associated with lower serum cholinesterase and poorer outcomes. PON1 activity may be considered as an indicator of prognosis in OP poisoning.