Focal glomerulosclerosis and proteinuria in patients with solitary kidneys.

We have studied ten normotensive patients (nine male and one female, aged between 28 and 51 years) who each had a solitary functioning kidney and proteinuria. Six had undergone unilateral nephrectomy, and four unilateral renal agenesis. In each case, intravenous pyelography revealed only one functioning kidney with compensating hypertrophy. Mild to moderate chronic renal failure was present in six, and microhematuria in two. Proteinuria ranged from 1.10 to 4.10 g/24 hr, being in the nephrotic range in three patients. In seven patients, a renal biopsy showed focal glomerulosclerosis. Immunofluorescence studies demonstrated granular deposits of IgM in three and C3 in six cases, over the sclerotic areas. We suggest that the appearance of proteinuria and focal glomerulosclerosis in a patient with a solitary kidney could be due to chronic glomerular hyperfiltration.