Acute kidney failure from ingestion of "wood bleach" beekeeping miticide

Wood bleach is >95 % oxalic acid formulation used off-label as a miticide for Varroa mites by hobbyist beekeepers. Wood bleach (oxalic acid) ingestions are poorly documented in the medical literature. A 46-year-old man presented to the emergency department nauseated and vomiting after accidentally ingesting "bleach and grain ethanol intended for use in beekeeping." Initial evaluation was reported to the regional Poison Center as a creatinine concentration of 2.46 mg/dL (217 μmol/L); he was otherwise well. He was volume resuscitated and discharged home without further evaluation. Four days later, he returned with worsening nausea and vomiting, endorsing ongoing intentional use of the mixture as an intoxicant. He was fully oriented, in no distress, with normal vital signs but for blood pressure of 175/110 mmHg. Investigations revealed a serum creatinine of 16.8 mg/dL (1485 μmol/L) and a high anion gap metabolic acidosis (pH 7.3, bicarbonate 15 mmol/L, anion gap 29). Crystalluria testing was deferred due to anuria. Fomepizole, supplementary thiamine and pyridoxine were administered for suspected occult toxic alcohol poisoning; hemodialysis was initiated the same evening. Ethylene glycol resulted undetectable. Renal biopsy revealed oxalate nephropathy. It was revealed the mixture contained 'wood bleach,' or > 95 % oxalic acid, rather than reported sodium hypochlorite. Hemodialysis continued at 2-week follow-up. Presentations of anion gap metabolic acidosis in those who practice beekeeping should prompt consideration of oxalic acid toxicity. Early nephrology consultation may be needed to facilitate hemodialysis to prevent or treat metabolic acidosis and renal failure.