Sustained remission of post-Fontan protein-losing enteropathy achieved by combination therapy with high-dose spironolactone and the somatostatin analogue octreotide: a case report

Protein-losing enteropathy (PLE) is a serious complication affecting approximately 5–12% of patients following the Fontan procedure for congenital heart disease and is associated with high mortality. Its pathophysiology is multifactorial, involving elevated central venous pressure, abnormal intestinal lymphatics, and altered mesenteric vascular resistance. No gold-standard therapy has been established, and current management approaches include hemodynamic optimization, nutritional therapy, and medications such as somatostatin analogues and spironolactone. Though spironolactone is frequently used as part of maintenance therapy, reports suggest that high-dose administration may be required in refractory cases. A case of post-Fontan PLE successfully treated with a combination of high-dose spironolactone and the somatostatin analogue octreotide, followed by sustained remission after tapering and discontinuation of octreotide, is described. A 5-year-old Japanese girl with complex congenital heart disease, including double-outlet right ventricle, pulmonary atresia, and complete atrioventricular septal defect, presented with acute abdominal pain, diarrhea, hypoalbuminemia, and systemic edema four years after undergoing a Fontan procedure. Laboratory evaluation showed marked hypoproteinemia and elevated fecal α1-antitrypsin, and imaging and endoscopy demonstrated intestinal lymphangiectasia. Her central venous pressure was increased to 18 mmHg. She was diagnosed with post-Fontan PLE. Standard-dose spironolactone (1.0 mg/kg/day), octreotide, and nutritional modification produced minimal improvement. Escalation of spironolactone to 6.2 mg/kg/day was followed by progressive resolution of hypoproteinemia. Octreotide was transitioned to intramuscular administration and later tapered. The patient was discharged on hospital day 44. Over long-term follow-up, central venous pressure remained controlled, fecal α1-antitrypsin remained < 40 mg/dL, spironolactone was gradually reduced to 1 mg/kg/day over five years, and octreotide was fully discontinued after eight years. She has maintained remission for more than 1.5 years following octreotide withdrawal. This case demonstrates that combination therapy with high-dose spironolactone and octreotide can induce remission in post-Fontan PLE unresponsive to standard-dose therapy. Importantly, both medications were successfully tapered, allowing discontinuation of octreotide while maintaining long-term remission. High-dose spironolactone may be an effective therapeutic option, particularly when used alongside somatostatin analogues, and it may help reduce prolonged octreotide exposure in children at risk of endocrine adverse effects. Further studies to evaluate optimal dosing and long-term safety are needed.