Endocrine Abstracts

Introduction: Insulinoma is a rare functional pancreatic neuroendocrine tumour affecting 1 in 4 million individuals per year. The inappropriate hyperinsulinemic state in this condition causes hypoglycaemia resulting in a broad spectrum of clinical manifestations including sweating, shaking, confusion, and seizure.

Case report: An 84-year-old lady was admitted to the hospital after sustaining a witnessed generalised tonic-clonic seizure during the early morning hours associated with having capillary blood glucose of 1.8 mmol/l. She had a history of multiple episodes of involuntary arms and legs shaking at night since a year, she was diagnosed with Rapid Eye Movement sleep behaviour disorder for which she was commenced on Clonazepam that failed to improve her symptoms. The patient developed multiple spontaneous hypoglycaemic episodes during this hospital admission and was found to have inappropriately elevated insulin levels (100 pmol/l) and high C-peptide (1048 pmol/l) during one of the episodes when her plasma glucose was 1.6 mmol/l. The urine sulphonylureas screen was negative. A hyper-vascular 1.3 × 0.9 × 1.3 cm tail of the pancreas mass suggestive of insulinoma was detected on the contrast enhanced CT scan of the abdomen with no radiologic evidence of distant metastasis. The patient elected for medical management, Diazoxide was preferred by our patient for its oral route of administration, and was commenced resulting in significant improvement in her symptoms and was well tolerated.

Conclusion: Insulinoma frequently gets misdiagnosed due to its rare occurrence and because of its wide spectrum of neuroglycopenic and autonomic symptoms that could be at times vague in nature mimicking other neuropsychiatric disorders, as highlighted in this case report. Detailed and careful history taking including obtaining a collateral history remains an essential tool allowing early suspicion of this uncommon diagnosis.