A 22-year-old man presented to the ED with vomiting, altered mental status, and fever. The patient’s roommate states that the patient has not been feeling well for 2 days, yesterday was complaining of fever and headache. This morning the patient had a new-onset seizure and altered mental status. The patient’s roommate is not aware of any history of drug abuse other than marijuana. In the ED, a CT scan was done and did not show any acute intracranial pathology. Urine toxicology screen was positive for cannabis. A lumbar puncture was done in the ED and resulted cell count consistent with viral meningitis/encephalitis. Cerebrospinal fluid herpes simplex virus (HSV) PCR and bacterial cultures were ordered, and results are pending. The patient was started on empirical vancomycin, ceftriaxone, and acyclovir. The patient was admitted to the ICU for monitoring. The next day, the patient’s mental status improved and the patient was transferred out of the ICU to the medical floor. The following day (48 hours after admission), the patient starts to have nausea, oliguria, abdominal, and flank pain. Repeated blood works were significant for:
Urine analysis shows white blood cells 5 cells/HPF, red blood cells 5 cells/HPF, protein 100 mg/dL, and crystals.
Which of the following is the MOST LIKELY cause of acute kidney injury (AKI)/failure in this patient?
A. VancomycinCorrect Answer: C
This patient presented to the ED with possible HSV encephalitis/meningitis. The patient was started on empirical antimicrobial, including acyclovir. After appropriate treatment with acyclovir, the patient mental status improved but developed AKI. Acyclovir and vancomycin, both are nephrotoxic. Acyclovir can cause AKI by forming crystals that precipitate in renal tubules. Vancomycin, on the other hand, does not cause crystal-induced nephropathy. Acyclovir crystal– induced nephropathy can be asymptomatic or present with nausea, abdominal pain, flank pain, asterixis, multifocal myoclonus, seizures, hallucination, and altered mental status. Symptoms typically within 24 to 48 hours after therapy. Crystal-induced nephropathy can be avoided by appropriate volume repletion before starting acyclovir infusion, slow IV acyclovir infusion over 1 to 2 hours, and dose adjustment for patients with renal impairment. Treatment of acyclovir crystal–induced nephropathy range from IV hydration and loop diuretics to hemodialysis depending on the severity of symptoms.
There are case reports for AKI associated with synthetic marijuana. There are reports of calcium oxalate crystal on kidney biopsy of patients who had renal impairment associated with synthetic marijuana abuse. As the patient does not have a history of synthetic marijuana abuse, it is less likely to be the cause of his renal impairment. Conventional urine drug screen does not test for synthetic marijuana.
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