Acute kidney injury due to crystalluria following acute valacyclovir overdose

A 49-year-old man was admitted to the hospital with an acute overdose of olanzapine 2.5 g, venlafaxine-XR 4.2 g, valacyclovir 30 g, and alcohol (blood alcohol concentration on admission 0.21%). On arrival he was hypotensive (87/57 mm Hg), tachycardic (135/min), and sedated with a lactic acidosis (5.8 mmol/l). His blood pressure increased to 129/75 mm Hg following 2 l fluid resuscitation and venous lactate concentration decreased to 2.1 mmol/l. His serum creatinine concentration was 104 μmol/l on admission (baseline concentration 65 μmol/l), but increased to 223 μmol/l the following day in the absence of other clinical abnormalities. Acyclovir-induced crystalluria was suspected, and so oral fluid intake was increased to 4–5 l/day. The creatinine concentration peaked at 538 μmol/l at 72 h and resolved over 1 week. Analysis of urine from the time of admission demonstrated pH 5.0, specific gravity 1.015, and birefringent needle-shaped crystals (see Figure 1) on a spun specimen (matching previous descriptions of acyclovir crystals). Repeat urinalysis during recovery was normal. Thrombocytopenia was also noted, with a nadir of 87 × 109/l at 48 h post-ingestion.