Acyclovir crystalluria.

Acyclovir crystals in the urine of a 28-year-old woman are described. The patient received intravenous acyclovir for herpes encephalitis. The crystalluria was accompanied by impairment of the renal tubules as evidenced by increased urinary beta-2-microglobulin excretion. Consecutive series of 60 patients on oral acyclovir and 20 patients on intravenous acyclovir were studied in order to define the frequency of acyclovir crystalluria. None of the patients studied had crystalluria, and none elevated serum creatinine levels. It is suggested that acyclovir crystalluria might be an early sign of acyclovir crystal nephropathy.