Endocrine Abstracts

Background: Insulinoma is the most common cause of hypoglycaemia due to endogenous hyperinsulinemia. However, they can sometimes present with atypical features. Some of the patients can also develop serious adverse effects to medical treatment. We present a case with atypical features and further developed serious adverse effects with medical treatment for insulinoma.

Case presentation: A 42-year-old Caucasian female presented with recurrent episodes of weakness and confusion, increasing in frequency for 5 years. She was previously diagnosed with type 1 vasovagal syncope, cephalic migraine and temporal lobe epilepsy for these symptoms; none entirely explaining the whole phenomenon. Patient’s capillary glucose incidentally measured during one such episode was 1.9 mmol/l and hence referred to the endocrine department for further evaluation. There was no history of chest pain, palpitations, presyncope or syncope during these episodes. There were no specific triggers or relationship with meals. Apart from Parkinson’s disease in some family members, rest of the medical history was unremarkable.On examination, the patient was hemodynamically stable and clinically unremarkable with a BMI of 20.9 kg/m². 24-hour fasting test demonstrated low but detectable levels of insulin (14 pmol/l) and c-peptide (121 pmol/l) with suppressed ketones (0.2 mmol/l) while the patient was hypoglycemic (2.2 mmol/l); sulphonylurea screen was negative. However, the patient had abnormally high insulin (187 pmol/l), c-peptide (1797 pmol/l) with hypoglycaemia (2.2 mmol/l) during mixed meal test. Rest of the endocrine hormonal assessment including gut hormone profile was within normal limits. CT scan of her abdomen revealed a 4.0×3.1 cm mass within the head and uncinate process of the pancreas.

Management and outcome: Patient developed a severe rash with diazoxide and life-threatening hypoglycaemia with octreotide when used as medical treatment for insulinoma. Medical therapy was hence discontinued and the patient went on for surgical resection of the mass following discussion with the neuroendocrine multidisciplinary team. Histology confirmed benign insulinoma and patient reported no further hypoglycemic episodes since the surgery. Genetic testing was not considered as this was a single lesion with normal serum calcium and no family history of neck operations.

Conclusion: Detectable levels of endogenous insulin with severe hypoglycaemia should prompt further investigations to rule out insulinoma. One should consider a possibility of insulinoma with an exaggerated insulin response to a mixed meal test. A close watch is recommended when patients are initiated on medical treatment for insulinoma.