Hematuria and red cell casts in typical diabetic nephropathy.

Hematuria and red cell casts are unusual urinary findings in patients with diabetic nephropathy. This glomerular disease is more typically characterized by the presence of moderate to severe proteinuria. Hematuria with red blood cell casts in patients with suspected diabetic nephropathy suggests the presence of a second, unrelated form of glomerulonephritis. The full clinical and renal pathologic findings in eight patients with otherwise typical diabetic nephropathy who also had significant hematuria and red cell casts in the urinary sediment are reported. Three of the patients had an immune-mediated form of glomerulonephritis identified. Careful histologic, electron microscopic, and immunofluorescent examination of the renal tissue from the remaining five patients demonstrated only diabetic nephropathy, without evidence of immune-mediated glomerulonephritis in any. Screening urinalysis in a population of 30 patients with diabetic nephropathy revealed hematuria in 30 percent and red cell casts in 13 percent. It is concluded that significant hematuria with red cell casts may be a clinical feature of diabetic nephropathy.