Hyperammonemia and hepatic status during valproate therapy.

The present study was conducted to assess correlation of ammonia levels with valproate levels in epileptic patients presenting with valproate toxicity and also whether liver enzymes and ammonia levels could serve as biochemical marker of valproate toxicity. 100 patients with epilepsy who had received valproate therapy for more than 12 months and had presented with valproate toxicity and 100 controls were included in the study. The serum valproate, ammonia and liver enzymes were measured in these subjects. In patients with valproate toxicity, the mean level of serum valproate was 110.91 ± 28.68 mg/dL (therapeutic range 50-100 mg/dL). Serum ammonia was higher (86.37 ± 39.90 µg/dL) in patients with valproate toxicity compared to controls (68.73 ± 30.07 µg/dL). Out of 100 patients, only 37 patients had serum valproate level > 120 mg/dL and 22 patients had raised levels of valproate as well as ammonia. Age < 30 years and serum ammonia > 69 μg/dL is risk factors for valproate toxicity. Serum ammonia, liver enzymes should be regularly investigated in patients on valproate therapy for early diagnosis of valproate toxicity.