Kidney Transplantation in Patients with Type 1 Diabetes Mellitus: Long-Term Prognosis for Patients and Grafts

Kidney transplantation is the best therapeutic choice to improve survival and quality of life in patients with end-stage diabetic nephropathy. Long-term prognosis in diabetic patients who recevied kidney transplants, however, has not been delineated. We, therefore, studied patient and graft survival, graft function and cause of graft failure in 78 Type I diabetic kidney transplant recipients in The Rogosin Institute/The Weill-Cornell Medical Center, New York who had functioning grafts for more than one year. The results were compared with 78 non-diabetic patients who had functioning grafts for more than one year and were matched for age, gender, donor source, time of transplantation and immunosuppressive therapy protocol. Cumulative patient survival rates for diabetic patients were significantly lower than those of non-diabetic patients (86% vs. 97% at 5 years and 74% vs. 95% at 10 years, respectively; p<0.05). The most common cause of death was cardiovascular disease. Graft survival rates for diabetic patients were also lower than that of non- diabetic patients (71% vs. 80% at 5 years and 58% vs. 72% at 10 years, respectively), but the differences did not reach statistical significance. Among the 22 failed grafts in diabetic patients, 7 (32%) were due to patient death rather than primary graft failure. If the patients who died with a functioning graft were censored, graft survival rates of diabetic patients approached those of non-diabetic patients (80% vs. 81% at 5 years and 65% vs. 73% at 10 years, respectively). Creatinine clearances in diabetic patients were lower than that in non-diabetic patients through the follow-up period, but the differences were significant only for the first few years. At no time was there a higher creatinine clearance for diabetic patients. Among the 16 patients who had transplant kidney biopsies two to seven years post-transplant, 6 showed morphological changes consistent with diabetic nephropathy. One patient lost graft function solely by recurrent diabetic nephropathy. We conclude that long-term patient survival for diabetic patients is significantly lower than that of non-diabetic patients, due primarily to cardiovascular disease. Graft survival is comparable between the two groups. Creatinine clearances of diabetic patients are lower than those of non-diabetic patients. There is no apparent glomerular hyperfiltration at any time in diabetic patients. Recurrence of diabetic nephropathy is a rare cause of graft failure in the first 10 year post-transplant period. Aggressive intervention to modify cardiovascular risk factors should improve patient and graft survival in diabetic kidney transplant recipients.

Urinary Stones following Renal Transplantation

BACKGROUND: The formation of urinary tract stones following renal transplantation is a rare complication. The clinical features of stones after transplantation differ from those of non-transplant patients. Renal colic or pain is usually absent and rarely resembles acute rejection. METHODS: We retrospectively studied 849 consecutive kidney transplant patients in The Rogosin Institute/The Weill-Cornell Medical Center, New York who were transplanted between 1980 and 1997 and had functioning grafts for more than 3 months, to determine the incidence of stone formation, composition, risk factors and patient outcome. RESULTS: At our center, urinary stones were diagnosed in 15 patients (1.8%) of 849 functioning renal grafts for 3 or more months. Of the 15 patients, 10 were males and 5 were females in their third and fourth decade. Eight patients received their transplant from living donors and 7 from cadaveric donors. The stones were first diagnosed between 3 and 109 months after transplantation (mean 17.8 months) and 5 patients had recurrent episodes. The stones were located in the bladder in 11 cases (73.3%), transplanted kidney in 3 cases and in multiple sites in one case. The size of stones varied from 3.4 mm to 40 mm (mean 12 mm). The composition of stones was a mixed form of calcium oxalate and calcium phosphate in 5 cases and 4 patients had infected stones consisting of struvite or mixed form of struvite and calcium phosphate. Factors predisposing to stone formation included tertiary hyperparathyroidism (n=8), hypercalciuria (n=5), recurrent urinary tract infection (n=5), hypocitraturia (n=4), and obstructive uropathy (n=2). Many cases had more than one risk factor. Clinically, painless hematuria was observed in 6 patients and dysuria without bacteriuria in 5 patients. None had renal colic or severe pain at any time. There were no changes in graft function at diagnosis and after removal of stones. Five patients passed stones spontaneously and 8 patients underwent cystoscopy for stone removal. CONCLUSION: Urinary stone formation following kidney transplantation is a rare complication (1.8%). Hyperparathyroidism, hypercalciuria, recurrent urinary tract infection and hypocitraturia are the most common risk factors, but often there are multiple factors which predispose to stone formation. To detect stones and determine their location and size, ultrasonography appears to be the most useful diagnostic tool. Prompt diagnosis, the removal of stones and stone-preventive measures can prevent adverse effects on renal graft outcome.