Case Report: Avermectin poisoning-associated hemolytic uremic syndrome

Avermectin, a commonly used agricultural pesticide and antiparasitic agent, typically causes acute human toxicity characterized by central nervous system depression and gastrointestinal disturbances. However, its association with thrombotic microangiopathy has not been previously reported. We describe a 60-year-old woman who developed anuria after ingesting 300 mL (15 g) of avermectin. Laboratory investigations demonstrated thrombocytopenia, microangiopathic hemolytic anemia, and acute kidney injury. Renal biopsy revealed thrombotic microangiopathy-like lesions. Thrombotic thrombocytopenic purpura and Shiga toxin-producing Escherichia coli-associated hemolytic uremic syndrome were excluded. Markedly elevated plasma levels of the terminal complement complex (C5b-9) confirmed complement activation, supporting the diagnosis of complement-mediated thrombotic microangiopathy. The patient subsequently received complement inhibition therapy with eculizumab during the disease course. Hematologic abnormalities resolved and renal function gradually recovered, allowing discontinuation of dialysis; however, a definitive causal relationship between eculizumab administration and clinical recovery cannot be established. This case suggests that avermectin poisoning may act as a potential trigger of complement-mediated TMA and highlights the importance of considering this in patients with severe pesticide intoxication complicated by unexplained TMA features.