Finerenone in Treating a 12-Year-Old Boy Suffering Gitelman Syndrome Without Causing Gynecomastia.

Gitelman syndrome (GS) is an autosomal recessive disorder caused by mutations in the SLC12A3 gene, characterized by hypomagnesemia, hypokalemia, alkalosis, and hypocalciuria. Finerenone, a non-steroidal mineralocorticoid receptor antagonist (MRA), has shown cardiorenal protective effects and improved prognoses in type 2 diabetes (T2DM) and chronic kidney disease (CKD). However, its use in non-diabetic nephrology has been infrequently reported. This report presents a case of a male child with GS who was treated with finerenone in combination with potassium and magnesium supplements to elevate potassium levels without experiencing gynecomastia. A 12-year-old boy with a 6-year history of recurrent hypokalemia was asymptomatic for fatigue, extremity numbness, and abdominal distension. He underwent renal biopsy, which suggested mild tubular injury, with no evidence of periglomerular hypertrophy. Genetic testing identified a heterozygous mutation in SLC12A3 at the p.Thr60Met site. Initial treatment with spironolactone, captopril, and electrolyte supplements led to breast overdevelopment. Subsequently, spironolactone was replaced with finerenone, while other therapies remained unchanged. A follow-up examination showed further improvement in potassium levels and no recurrence of breast development. This case suggests that the combination of finerenone, captopril, and electrolyte supplements may be a promising therapeutic approach for managing GS in children, particularly suitable for paediatric patients whose growth and development are affected by the use of steroidal mineralocorticoid receptor antagonists such as spironolactone.