Thrombotic Microangiopathy: An Under-Recognised Cause of Snake-bite-related Acute Kidney Injury

INTRODUCTION: Thrombotic microangiopathy (TMA) as a cause of snake-bite-induced acute kidney injury (AKI) is rarely reported. Very little is known about the clinical course, optimal management, and prognosis of this entity. We describe a series of snake-bite-induced TMA and compare their outcomes with those without TMA. METHODS: This was a single-center retrospective study of patients with AKI following snake envenomation admitted between January 2012 and December 2017. Demographic profile, clinical parameters, and outcomes were studied. TMA was diagnosed based on presence of triad of microangiopathic hemolytic anemia, thrombocytopenia, and AKI, and groups with and without TMA were compared. RESULTS: Of 103 patients with AKI following snake bite, 19 (18.5%) had clinical evidence of TMA. All patients with TMA had advanced azotemia (mean peak serum creatinine 9.5 ± 3.0 mg/dL), with 18 (95%) requiring renal replacement therapy (RRT). Thirteen (68%) had either complete or partial recovery of renal functions, two (10%) progressed to end-stage renal disease, and one died (three patients were lost to follow-up). Age ≥50 years, presence of oliguria/anuria, anti-snake venom dose ≥10 vials, and urea ≥80 mg/dL at presentation were independently associated with TMA (P < 0.05). RRT requirement (95% vs. 57%), mean number of RRT sessions (18 vs. 4.5 sessions), and hospital stay ≥7 days (84% vs. 58%) were higher in patients with TMA (P < 0.05), but patient outcomes did not differ. CONCLUSIONS: In conclusion, TMA was seen in 18.5% of patients with snake-bite-related AKI in our study and was associated with almost universal need for RRT, longer duration on RRT, and hospital stay compared with patients without TMA.