Serum creatine phosphokinase: a probable marker of severity in organophosphorus poisoning

Organophosphorus (OP), the commonest agent for poisoning in India due to its easy availability, acts by inhibiting acetylcholinesterase at muscarinic and nicotinic receptors. Erythrocyte cholinesterase (EchE) and plasma cholinesterase (PchE) are reduced in OP poisoning, but their estimation is costly and not regularly performed. There are emerging options for new cheaper biochemical markers in relation to OP poisoning. Serum level of creatine phosphokinase (CPK) is often found to be elevated in OP poisoning. This study was conducted to see if CPK may be used as an alternative of cholinesterase levels in blood to assess the severity of OP poisoning. This was a prospective and observational study. Sixty-three patients of OP poisoning without any prior treatment, presenting within 6 hours, were selected and their clinical severity was categorized according to Peradeniya organophosphorus poisoning (POP) scale. Level of serum CPK, blood EchE and pH were measured following admission, and total dose of atropine (mg) until the final clinical outcome (complete recovery or death) was calculated. Student's t-test and Pearson's correlation coefficient was used for the assessment of statistical significance. According to POP scale, clinical severity was mild (score 0-3) in 17 (27%), moderate (score 4-7) in 32 (50.8%) and severe (score 8-11) in 14 (22.2%) patients. Serum CPK, EchE level, blood pH and total atropine dose strongly correlated with clinical severity. Our study recommends serum CPK as an alternative marker.