McArdle's disease presenting as recurrent cryptogenic renal failure due to occult seizures.

Myophosphorylase deficiency (McArdle's disease) may present with episodic renal failure following exertion. We present a case of adult-onset myophosphorylase deficiency in which recurrent bouts of renal failure could not be associated with any exertional events until a tonic seizure was witnessed after the fourth episode of renal failure. In the absence of a clear exertional cause for myoglobinuria, an occult seizure disorder should be suspected.