Mistaken Mushroom Poisonings

A 38-year-old man in prior excellent health presented to the emergency department (ED) with severe nausea and vomiting 4 hours after consuming homemade soup containing parts of 4 wild mushrooms he had picked that day (Figure 1). He described the mushrooms as having straight 4-inch stems (stipes) and bright white caps. His vital signs were unremarkable. Supportive therapy with antiemetics and intravenous (IV) fluids was initiated. Baseline laboratory studies included serum blood urea nitrogen (BUN), 10 mg/dL (3.6 mmol/L), and creatinine, 1.0 mg/dL (88.4 μmol/L). His complete blood count, electrolytes, and hepatic transaminases were within normal limits. Because his gastrointestinal symptoms resolved with supportive care and his laboratory studies remained normal, he was discharged from the ED after 8 hours of observation. Five days later, he was readmitted to the ED with a history of anorexia and 8 hours of anuria. What is your diagnosis? How would you manage this case? The diagnosis was Amanita smithiana mushroom poisoning with reversible acute renal failure after the misidentification (and ingestion) of nephrotoxic A smithiana mushrooms (Figure 1) mistaken for look-alike edible North American matsutake or pine mushrooms, Tricholoma magnivalere. The nephrotoxic A smithiana, or Smith's Amanita (Figure 1), is often mistaken for the edible and highly sought after North American matsutake or pine mushroom, T magnivalere, a frequent export to Japan where it rivals the Asian matsutake mushroom, T matsutake, in popularity. Accidental ingestion of A smithiana will cause gastrointestinal toxicity within 6 hours followed by acute renal failure within 2 to 6 days. After the diagnosis has been made, the laboratory biomarkers of renal function should be reassessed, and preparations for temporary hemodialysis should be instituted. On readmission to the ED, the patient's BUN was 77 mg/dL (27.5 mmol/L), and his creatinine was 14 mg/dL (1237.6 μmol/L). A dialysis catheter was inserted for rapid hemodialysis for acute renal failure. After 12 days of inpatient dialysis, his BUN and creatinine returned to normal ranges, and he was discharged from the hospital. His dialysis catheter was removed in the nephrology clinic 4 days later.