March hemoglobinuria-associated acute tubular injury

A previously healthy 17-year-old African-American male presented with acute kidney injury after playing basketball without rest for 5–6 h. At presentation, his serum creatinine was 468.5 μmol/L (5.3 mg/dL) with an estimated glomerular filtration rate (eGFR) of 17 mL/min/ 1.73 m calculated by the four-variable modification of diet in renal disease study equation. He had no history of kidney disease and was not taking any medications. Serum creatine kinase was elevated at 2277 U/L (reference range: 9–185 U/L) and his unconjugated bilirubin was 75.2 μmol/L (4.4 mg/dL). Hemoglobin was 133 g/L (13.3 g/dL) and a direct agglutination test was negative. Serum haptoglobin and hemoglobin electrophoresis studies were not done. Due to concern for rhabdomyolysis-associated acute tubular injury/necrosis, a kidney biopsy was performed. Seventeen glomeruli were sampled and were histologically unremarkable. Proximal tubules showed marked attenuation of brush borders and epithelial cell flattening. Granular cast material was identified within distal tubular lumina, which stained weakly by periodic acid–Schiff (PAS) reagent (Figure 1A) and eosinophilic on the hematoxylin and eosin stain (Figure 1B). Immunohistochemical staining for myoglobin was negative (Figure 1C); however, hemoglobin A diffusely and strongly stained the cast material (Figure 1D). A Prussian blue histochemical stain was negative for hemosiderin deposition. No glomerular, tubular basement membrane or interstitial deposits were seen by immunofluorescence or electron microscopy. The biopsy was interpreted as acute tubular injury/necrosis with hemoglobin casts, suggestive of hemolysis-associated acute kidney injury.