No evidence of impaired oral hormone substitution after gastric bypass surgery in patients with morbid hypothalamic obesity and hypopituitarism secondary to craniopharyngioma

Abstract

Background: Craniopharyngiomas (CP) are benign brain tumors presenting in childhood treated by tumor resection together with radiotherapy. In about half of the cured patients hypothalamic damage leading to eating disorders and obesity as well as to hypopituitarism, necessitating consequent hormone substitution therapy, is observed. Bariatric surgery is an efficient treatment strategy for morbid obesity. However, so far it is unknown, whether oral hormone substitution is hampered by impaired intestinal absorption, leading to severe hypopituitarism or adrenal insufficiency. Methods: 4 CP-patients with hypopituitarism and morbid obesity treated by gastric bypass surgery were included in this retrospective analysis. Dosage of hormone substitution, hormonal blood concentrations, adverse effects of impaired drug absorption and anthropometric characteristics were investigated pre and 3 to 12 months post operatively. Results: In all CP-patients (3w/1m; BMIbasal 49 +/- 7kg/m2) gastric bypass resulted in distinct weight loss (-35 +/- 27kg). In follow-up examinations mean concentration of fT4 increased (fT4basal 0.9 +/- 0.31ng/dl vs fT4FollowUp 1.28 +/- 0.29ng/dl). No patient developed any signs of adrenal insufficiency postoperatively. Mean daily dosage of oral thyroid hormone substitution (levothyroxinebasal 156 +/- 44mug/d vs levothyroxineFollowUp 150 +/- 30mug/d) and hydrocortisone (hydrocortisonebasal 29 +/- 12mg/d vs hydrocortisoneFollowUp 26 +/- 2mg/d) was unchanged. Mean insulin- like-growth-factor-1 concentration decreased after weight loss (IGF-1basal 217 +/- 93ng/ml vs IGF-1FollowUp 111 +/- 36ng/ml), whereas daily growth-hormone substitution was slightly increased (somatotropinbasal 0.9 +/- 0.5mg/d vs somatotropinFollowUp 1.0 +/- 0.4mg/d). Discussion: Our results in n=4 CP patients suffering from hypopituitarism indicate that oral hormone substitution is not impaired following gastric bypass operation, probably making it a safe and considerable treatment strategy in patients suffering from hypothalamic obesity.