Ultrastructural changes in renal tubules associated with glomerular bleeding.

Renal biopsies from ten patients presenting with macroscopic or heavy microscopic hematuria, shown to be glomerular in origin, were examined by light and electron microscopy. All biopsies showed erythrocytes within tubules by light microscopy and, in five cases, there were morphologic features of acute tubular necrosis. In four biopsies there was clear evidence by electron microscopy of uptake of erythrocytes by renal tubular epithelial cells, associated with some blunting of epithelial microvilli, vacuolar change and increased lysosomal content. Associated with erythrophagocytosis, the subsequent pathway of erythrocyte destruction within renal tubular epithelial cells closely resembled the hemolytic pathway described in macrophages of the reticuloendothelial system.