Clinical course of late-onset bone marrow transplant nephropathy.

Late-onset renal insufficiency is an increasingly recognized complication of bone marrow transplantation (BMT) which occurs between 6 and 12 months after BMT. This syndrome, which has occurred in 25% of our 2-year survivors, is characterized by azotemia, hypertension, and disproportionate anemia. A minority of our subjects have had a presentation similar to hemolytic-uremic syndrome, with rapid decline in kidney function. The others have had slower declines in kidney function, without apparent ongoing hemolysis. Stabilization of function has occurred in about one third of cases. Light microscopy has shown mesangial and endothelial cell dropout with widening of glomerular capillary loops. Electron microscopy has shown a striking subendothelial expansion of the glomerular basement membrane. This syndrome is similar to acute radiation nephritis. Stabilization of kidney function has occurred in some cases, perhaps reflecting control of the blood pressure. Studies of the prevention of this condition are needed because of the frequency of its occurrence and the growing number of BMT worldwide.