A Case of Oral Valacyclovir–Induced Acute Kidney Injury

Acute kidney injury (AKI) is defined as a rapid reduction in kidney function (within 48 hours) as measured by an increase in serum creatinine level, decrease in urine output, or need for renal replacement therapy, or all of the above. Herein, we present a rare case of AKI induced by oral valacyclovir. Nephrotoxicity due to valacyclovir is caused by intratubular precipitation of acyclovir crystals. A 39-year-old woman presents with acute onset of nonspecific reports of low back pain, nausea, and vomiting. After determining there was an AKI, the patient was treated with intravenous fluids and was monitored for improvement. The cause was deduced to be oral valacyclovir, which was being used to treat herpes labialis, and ultimately caused crystal-induced nephrotoxicity. Due to the rapid speed of renal excretion, acyclovir can surpass the solubility, and hence crystals can accumulate in the distal and collecting ducts. This can cause the symp-tomatology such as in this patient. In this case presentation and discussion, we re-view the presenting symptoms, diagnostic testing, differentials, and pathophysiology regarding crystal-induced AKI, specifically from valacyclovir.