Endocrine Abstracts

A 37-year-old female was referred with recurrent episodes of altered consciousness and disorientation. She described a three-year history of recurrent “funny turns”. They started with a sensation of warmth accompanied with cold sweat followed by unfamiliarity with the surroundings and cognitive impairment. The attacks increased in frequency gradually over time. There was a tendency for the attacks to occur in the morning, before bed and 3–4 hours after food. The patient didn’t gain weight and found that eating more frequent meals minimises symptoms. Past medical history, family history and drug history were unremarkable. Two random glucose samples 2.7 and 3 mmol/l (at 11:00 and 17:00 hours respectively) were low. Full blood count, urea and electrolytes, thyroid function test, liver function tests, bone profile and short synacthen tests were all normal. Supervised fasting provoked hypoglycaemia (blood glucose 2 mmol/l) with inappropriately high insulin (610 pmol/l), C-peptide (411 pmol/l) and pro-insulin (23 pmol/l) levels with no evidence of ketonemia. Sulphonylurea was not detected in any of the samples. A diagnosis of insulinoma was made. Prolactin levels and gut hormone profile were normal. The patient was started on diazoxide 300 mg/day that resulted in improvement in her symptoms and fasting glucose of 3.6–4.2 mmol/l, but she was developing hypertrichosis. CT scan of the Abdomen was normal. Endoscopic ultrasound failed (EUS) to localise the tumour despite good views of the pancreas. Octreotide scan showed no focus of increased activity. Pancreatic MRI showed a 1.7×2.6 cm tumour in the pancreatic tail. Intraoperatively a single pancreatic tumour, consistent with that found on MRI, was found and resected. The histology was consistent with an insulinoma. The patient’s symptoms improved after surgery.

Our patient had an insulinoma, which was localised by abdominal MRI preoperatively while EUS failed to localise the tumour. The literature suggests EUS has far higher sensitivity in detecting insulinomas (65–90%) compared to CT (30%) and MRI (as low as15% in some series). Lesions in the pancreatic tail as in our patient may however be missed. MRI scan of pancreas should be included in the initial assessment of such patients.