Safety and Effectiveness of Spironolactone to Reduce Proteinuria in Kidney Transplant Recipients During a 5-Year Follow-Up.

OBJECTIVES: Objectives: Posttransplant proteinuria is a biomarker of renal injury, negatively affecting graft function and survival. Aldosterone is involved in renal allograft damage, and its blockade can be beneficial. This study analyzed the long-term effect of spironolactone on proteinuria and graft function in kidney transplant recipients.

MATERIALS AND METHODS: We conducted a retrospective single-center study of kidney transplant recipients ≥18 years old with persistent posttransplant proteinuria (measured as urine protein-to-creatinine ratio >0.5 for more than 6 months), who were treated with spirono-lactone and followed for 5 years. Patients were grouped by initial proteinuria as mild (<1), moderate (1-3), and severe (>3). Effects of spironolactone alone or combined with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers were analyzed.

RESULTS: Among 138 included patients, 119 received spironolactone monotherapy: 23 (19.%) had mild proteinuria, 75 (63.0%) were moderate, and 21 (17.7%;) were severe. In the moderate group, proteinuria significantly reduced from 1.4 (1.0-2.6) to 0.8 (0.2-7.7) at month 1 and 0.7 (0.1-3.8) at month 5. In the severe group, proteinuria also significantly reduced at year 1 from 5.4 (3.2-9.1) to 1.4 (0.2-11.6) (P < .05) and at year 5 to 0.5 (0.1-3.1) (P < .05). Nineteen patients received spironolactone associated with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers: 12 (63.1%) had moderate proteinuria and 7 (36.9%) had severe proteinuria. In the moderate group, proteinuria significantly decreased to 0.9 (0.1-5.2) after 2 years compared with baseline of 1.6 (1.0-2.4), reaching 0.6 (0.1-3.5) in year 5. In the severe group, proteinuria decreased during 2 years from 5.6 (3.3-8.9) to 1.5 (0.9-3.7) (P < .01) and reached 1.7 (0.3-3.1) in year 5. Renal function remained stable, and graft survival rate was similar among groups.

CONCLUSIONS: Long-term treatment with spironolactone effectively reduced posttransplant proteinuria in kidney transplant recipients with initial proteinuria >1, preserving graft function.