Endocrine Abstracts

Introduction: The metabolic stressor, hypoglycemia, elicits integrated counterregulatory responses, including activation of the hypothalamic–pituitary–adrenal axis. However, it is suggested that recurring insulin-induced hypoglycemia can impair this counter-regulation. Here we report three cases of patients with isulinoma and corticotroph deficiency.

Case reports: The first case, 38-year-old man was referred because of recurrent episodes of hypoglycemia. Hormonal investigations were in favour of dissociated anterior pituitary failure, with growth hormone and corticotroph deficiency. The hypothalamic-pituitary MRI was normal. The fasting test argued in favour of a hyperinsulinemic hypoglycemia. The abdominal scan and the endoscopic ultrasound showed a mass within the tail of the pancreas. Distal pancreatectomy was performed. Histology disclosed an insulinoma. On follow up, no hypoglycemic episodes recurred and cortisol and GH response to induced hypoglycemia was normal. The second case, 68 years old man referred for investigation of hypoglycemic episodes. He was diagnosed with corticotroph deficiency and hypergonadotropic hypogonadism with negative investigations. The hypothalamic-pituitary MRI was normal. After treatment with glucocorticoids, hypoglycemic episodes were significantly improved. After 6 years, he presented severe hypoglycemia and investigations revealed a 1.5 cm tumor in the head of the pancreas with hepatic and pulmonary metastases. The third case, 38 years old woman with a history of primary hypothyroidism for 6 years, presented with symptomatic hypoglycemia and a history of weight gain. Laboratory investigations argued in favour of a hyperinsulinemic hypoglycemia and the abdominal scan showed a mass within the tail of the pancreas. Furthermore, she was diagnosed with corticotroph deficiency. The hypothalamic-pituitary MRI was normal.

Conclusions: Our clinical cases show that hyperinsulinemia and hypoglycemia in patients with insulinoma can give rise to functional corticotrophin deficiency. The pathophysiological mechanism of this defective counter-regulation remains to be clarified; some studies suggest it could be related to hyperinsulinemia-induced decreased in CRF secretion.