Recurrent episodes of bizarre behavior in a boy with ornithine transcarbamylase deficiency: diagnostic failure of protein loading and allopurinol challenge tests.

Recurrent episodes of bizarre behavior were the only clinical symptoms that finally led to the diagnosis of ornithine transcarbamylase deficiency in an 8-year-old boy. The suspected diagnosis could not be confirmed with the use of current challenge tests. The response to a high-protein diet for 24 hours appeared to be a helpful diagnostic aid.