Effectiveness and Safety of Spironolactone in the Treatment of IgA Nephropathy: A Retrospective Self-Controlled Study.

Introduction: It is crucial to utilize combination therapy for immunoglobulin A nephropathy (IgAN) patients to reduce proteinuria and maintain stable kidney function. We demonstrate the safety and efficacy of low-dose spironolactone in the management of IgAN patients.

Methods: Adult IgAN patients treated with spironolactone were evaluated. Patients were separated into two categories according to whether 24-h proteinuria was reduced by more than 20% after 2 months of spironolactone treatment compared to baseline levels.

Results: Eighty-eight patients were analyzed and 24-h proteinuria decreased from 0.93 g to 0.70 g (p < 0.001) after 2 months of treatment with spironolactone, accompanied by a slight decrease in eGFR from 75.7 to 73.9 mL/min/1.73 m2 (p = 0.033). Intriguingly, 47 patients in the effective mineralocorticoid receptor antagonist (MRA) group showed less endocapillary hypercellularity (p = 0.040). In the ineffective group, 18 patients discontinued MRA treatment because 24-h proteinuria increased from 0.83 g to 1.04 g, while the other 23 patients continued with spironolactone and proteinuria decreased to 0.57 g in the sixth month (p = 0.001). Furthermore, 12 patients with persistent high proteinuria during prednisone therapy were added with spironolactone. 24-proteinuria was dropped from 0.95 g to 0.73 g at the second month and to 0.50 g at the sixth month.

Conclusions: In our study, we confirmed spironolactone's efficacy in reducing urine protein excretion in IgA nephropathy patients within 2 months of treatment. However, response varied among patients, with those showing endocapillary proliferation (E1) in renal biopsies having poor spironolactone responsiveness. Administering MRAs to patients with eGFR over 30 mL/min did not result in hyperkalemia, indicating the treatment's safety.