Endocrine Abstracts

A 45-year-old man with obesity (BMI 36 kg/m²) was admitted with a 12-hour history of headache and confusion and managed for viral meningitis. Treatment was discontinued after CSF viral PCR was negative. At presentation, he was hypoglycaemic with a capillary glucose of 1.6 mmol/l. Past medical history was not significant and there were no similar episodes previously. He denied taking insulin, other medications, illicit drugs or alcohol. Initial investigations revealed normal full blood count, liver and kidney function tests, C-reactive protein and normal CT head. Our patient continued to experience recurrent hypoglycaemic episodes. Biochemical investigations revealed normal pituitary hormone profile, thyroid function tests and coeliac screen. Short synacthen test (SST) revealed a baseline cortisol of 193 nmol/l and 30-min cortisol 407 nmol/l. Subsequently, SST was also abnormal. ACTH level was 4.3 pmol/l (2–11). Antiadrenal antibodies were negative. A diagnosis of idiopathic adrenal insufficiency was made and the patient initiated on oral hydrocortisone, but continued to have hypoglycaemic episodes. Serum insulin and insuin C-peptide levels were inappropriately elevated in keeping with endogenous hyperinsulinaemia (serum insulin 276 pmol/l, insulin C-peptide – 1756 pmol/l) during a hypoglycaemic episode on the 72-h fasting test. Somatomedin C was normal {17.2 nmol/l (7.7–26)}. CT abdomen with contrast revealed a 2.3×2.1 cm lobulated mass in the pancreatic tail. The patient was initiated on diazoxide and referred to a pancreatic surgeon. He underwent partial-pancreatectomy and histology revealed an insulinoma. Adrenal insufficiency persisted for 12 months (base line and 30-min cortisol, 159 and 418 nmol/l respectively) and only resolved after 15 months (baseline cortisol and 30 min cortisol 259 and 520 nmol/l), when hydrocortisone was stopped. The combination of insulinoma and transient adrenal insufficiency is rare; our case report suggests a potential association, highlighting the need for further research.