Renal Hemosiderosis Associated with Mitral Regurgitation Detected by Severe Proteinuria Due to Congestion.

A 53-year-old woman with an atrioventricular septal defect who had undergone 3 valvuloplasties by 7 years old underwent a kidney biopsy because of lower extremity edema and proteinuria. The glomeruli were intact; however, the proximal tubules showed marked hemosiderin deposition, which was assumed to be related to a fissure in the calcified cardiac patch. The fissure acts as a collateral blood channel from the left ventricle to the left atrium, and the resulting mitral regurgitation and backflow of blood cause turbulent flow phenomena and chronic hemolysis. After hospitalization and dietary guidance on salt reduction, the edema improved, and the proteinuria disappeared.