Serum acetylcholinesterase and prognosis of acute organophosphate poisoning

OBJECTIVE: The aim of this study is to investigate the prognostic value of serum acetylcholinesterase levels and their relationship with neurological syndromes (Type 1 syndrome, intermediate syndrome, and delayed polyneuropathy) in acute organophosphate poisoning. MATERIALS AND METHODS: Thirty-two consecutive patients with acute organophosphate poisoning admitted to the Ondokuz Mayis University Emergency Department from June 1999 to January 2001 were evaluated. Patients were assessed according to admission time, symptoms, and results of clinical exams and their serum acetylcholinesterase levels were determined on days 1, 2, 3, 7, and the last day. RESULTS: There was no significant difference between the first-day serum acetylcholinesterase of the patients with severe poisoning (n = 22, 68.75%) and of the patients with mild poisoning (n = 10, 31.25%; NS). There was no discernible difference between the serum acetylcholinesterase obtained on days 1 and 3 after poisoning from the patients with intermediate syndrome (n = 5, 15.6%; means: 0.90 +/- 0.65 vs. 0.88 +/- 0.53, 19.35 vs. 18.92%; NS, sensitivity = 80%; specificity = 87.5%). There was a significant difference between the serum acetylcholinesterase obtained on days 1 and 3 from the patients with nonintermediate syndrome (n = 24, 75%; means: 1.05 +/- 0.24 vs. 1.68 +/- 0.29, 22.58 vs. 36.12%; p < 0.001). There was no discernible significant difference in serum acetylcholinesterase between the patients with organophosphorus-induced delayed polyneuropathy (n = 7, 21.8%) and nonorganophosphorus-induced delayed polyneuropathy. In the patients who died (n = 5, 15.6%), serum acetylcholinesterase showed no discernible increase day 1-the last day (means: 0.50 +/- 0.25 vs. 0.46 +/- 0.26, 10.75 vs. 9.89%; NS). There was a significant difference between the serum acetylcholinesterase levels obtained on days 1 and the last day from the patients who survived (n = 27, 84.3%; means: 1.14 +/- 0.25 vs. 2.32 +/- 0.26, 24.51 vs. 49.89%; p < 0.001). CONCLUSION: In the acute phase of organophosphate poisoning, low serum acetylcholinesterase (> 50% of minimum normal value) supports the diagnosis of organophosphate poisoning but it does not show a significant relationship to the severity of poisoning (NS). The serum acetylcholinesterase activity may be a useful parameter in following the acute prognosis of organophosphate poisoning.