Unexpected Improvement of Proteinuria Associated With Focal Segmental Glomerulosclerosis Following Adherence to Continuous Positive Airway Pressure: A Case Report

Focal segmental glomerulosclerosis (FSGS) is a progressive glomerular disease characterized by proteinuria and an increased risk of kidney failure. Although obstructive sleep apnea (OSA) is associated with adverse renal outcomes, improvements in FSGS-related proteinuria following OSA treatment have not been established. We report a 51-year-old female patient with biopsy-confirmed FSGS and persistent proteinuria, despite stable weight and maximal angiotensin II receptor blocker therapy, who was diagnosed with severe OSA (apnea-hypopnea index, 87.3 events/hour). Continuous positive airway pressure (CPAP) effectively controlled the OSA. Within 2 months, proteinuria decreased by 49%, accompanied by a reduction in blood pressure without any changes in medication. Renal function remained stable, and further improvement in proteinuria was observed with ongoing CPAP adherence. This case suggests that CPAP therapy in patients with concomitant FSGS and OSA may significantly reduce proteinuria and preserve renal function. Further studies are warranted to clarify the potential therapeutic benefits of CPAP in this patient population.