Intratubular hemoglobin casts in hemolysis-associated acute kidney injury.

Kidney injury is a complication of intravascular hemolysis associated with many forms of hemolytic disease. Reports of kidney biopsy findings in patients with hemolysis-related kidney injury have focused primarily on the accumulation of hemosiderin pigment within proximal tubular epithelial cells (hemosiderosis), a feature of chronic hemolysis. The nephrotoxic effects of hemoglobin include direct cytotoxicity to tubular cells, but hemoglobin also can precipitate in distal nephron segments, forming obstructive casts. We present a case of hemolysis-associated tubular injury, characterized by acute onset of intravascular hemolysis followed by acute kidney injury with acute tubular injury and abundant intratubular casts containing hemoglobin.