Hyperammonemia is associated with generalized convulsion.

Purpose: The possibility that hyperammonemia may be associated with generalized convulsion (GC) was retrospectively investigated.

Methods: Subjects comprised 17 patients with GC who were transported to our department and underwent analysis of serum biochemistry, including ammonia, since October 2004.

Results: Causes of convulsion included intracranial lesions (n=8), endocrine diseases (n=2), epilepsy (n=2) and others (n=5). Ammonia levels in all cases exceeded the upper limit of normal range. Ammonia levels in 8 subjects were re-checked on hospital day 2, and all were lower than levels on hospital day 1 without any treatment for hyperammonemia.

Conclusion: GC itself appears to be associated with hyperammonemia. Although hyperammonemia is also known to induce convulsion, biochemical analysis immediately after GC is not useful for diagnosing hyperammonemia-induced convulsion.