Snake bite: Biochemical changes in blood after envenomation by viper and cobra

Snake bite poisoning is a significant cause of mortality and morbidity in tropical and sub-tropical countries like India. The present study was taken up to evaluate the biochemical changes in snake bite cases in different time periods. The clotting time (C.T) was 55.83±38.5 in viper bite cases, much higher than in controls, 5.07±1.33, which was normalized after anti venom administration; however no significant changes were observed in cobra bite cases. Thus evaluation of C.T. may help to differentiate viper bites from cobra bites and to choose specific mono-valent anti-venom treatment. The blood urea level in viper bite cases increased significantly after the sixth hour: 58.19±27.6 mg% in cases; 25.80±4.9mg% in controls. Since anti-venom does not decrease the blood urea to normal, dialysis is required for normalization of urea level. Blood creatinine level in the majority of viper bite cases was found to be increased (1.60–7.4 mg%) after the sixth hour, where as in cobra bite cases it was found only in 9% (1.5-2mg%); this increased creatinine level in viper bite cases caused the renal failure. Sodium and potassium levels were not increased in both cobra and viper bite cases, up to the fourth day. However, in 50% of viper bite cases, significant elevation in sodium level was observed on 5th and 6th day, due to the secondary effect of renal failure. 50% of the viper and cobra bite cases showed rise in potassium level on the sixth day which ranged between 5.1– 4.14 mEq/litre. No significant difference was observed in serum calcium level between viper and cobra bite cases. In the present study, clotting time increases immediately after viper bite, detection of which within six hours is a good indicator of envenomation by viper bite. The other biochemical parameters would be helpful to assess the severity of renal failure predominant after six hours of envenomation.