Clinical Case Scenario
A 38-year-old previously healthy man was admitted following a snakebite to his lower limb. At presentation, he had progressive local swelling with evidence of systemic envenomation. His initial serum creatinine was 0.9 mg/dL, platelet count and hemoglobin were within acceptable limits, and urinalysis showed no significant proteinuria or hematuria.
He received polyvalent anti-snake venom (ASV) as per the clinical indication, along with supportive care. His clinical condition improved over the next 48–72 hours, with resolution of the acute manifestations of envenomation. Renal function remained stable, and he was subsequently discharged.
Ten days after receiving ASV, he returned with fever, generalized fatigue, intense pruritus and a widespread erythematous rash. He also complained of pain involving both knees, ankles and wrists, without significant morning stiffness. Examination revealed mild periorbital and pedal edema. He was hemodynamically stable, with no wheeze, stridor, hypotension or features of recurrent envenomation.
Investigations showed:
- Hemoglobin: 12.6 g/dL
- Platelet count: 2.1 × 10⁵/µL
- Serum creatinine: 1.9 mg/dL (baseline- 0.9 mg/dL)
- Serum potassium: 4.7 mmol/L
- Urinalysis: 2+ protein, microscopic hematuria
- Urine microscopy: dysmorphic RBCs with occasional RBC casts
- Urine protein–creatinine ratio: 1.2 g/g
- Serum C3: low
- Serum C4: low
- LDH: not significantly elevated
- Peripheral smear: no schistocytes
- Creatine kinase: within normal limits
There was no recent hypotension, nephrotoxic drug exposure, recurrent hemolysis or rhabdomyolysis.
Question
What is the most likely explanation for the new-onset acute kidney injury in this patient?
