Endocrine Abstracts

Case history: A 74 years old lady with background of hypertension and asthma had multiple admissions with funny turns, dizziness and double vision for at least 2 years. She was seen by various medical specialties including cardiology, stroke medicine and rheumatology before she was noticed to have a capillary glucose of 1.2 mmol/l. Whipple’s triad was demonstrated during evaluation. Supervised fasting confirmed biochemical evidence of endogenous hyperinsulinaemia with inappropriately high level of serum Insulin & C-peptide during hypoglycaemia and a negative Sulphonylurea screen.

Investigations: Biochemistry during supervised fast: Plasma Glucose-1.9 mmol, Plasma Insulin-7.6 mU/l, C-Peptide-746 pmol/l & negative Sulfonylurea screen. CT and MRI pancreas (2015 & 2018) - No pancreatic lesions or malignancy Ocreoscan NM scan with SPECT (July 2018): No evidence of Octreotide avid lesion Endoscopic Ultrasound (September 2018): 1.5 cm mass (with classic appearance of insulinoma) seen tucked between splenic vein and artery. It appeared to be wrapped around a non-dilated pancreatic.

Treatment: Although patient was successfully managed initially with dietary modification, symptoms progressed and Diazoxide was started with excellent results. She unfortunately developed severe peripheral oedema and weight gain necessitating reduction in dose of Diazoxide. As a result, she developed persistent hypoglycaemia. Despite lowering the dose of Diazoxide, she developed clinical features of heart failure (BNP>2400, Echo - Preserved ejection fraction) and eventually she decided to stop Diazoxide because of debilitating symptomatic fluid overload. This is when we localalised the tumour with EUS. At this point, she was setting alarm every hour during night to check for (& treat) hypoglycaemia. The fluid overload resolved and BNP normalized after stopping Diazoxide. She was then started on a trial of SC Octreotide despite negative Octreotide scan, which had a dramatic effect on her symptoms and blood sugar control. She has not had a single hypo since been on Octreotide for the last 3 months. She is now waiting for surgery.

Conclusion and points of discussion: 1. Although endogenous Insulin over secretion is rare, it should be considered in the differential diagnosis of patients presenting with symptoms suggesting hypoglycemia.

2. Capillary glucose should be tested in ALL unwell patients or with symptoms suggestive of hypoglycaemia

3. Glucose should be assayed by ALL blood gas analyzers (in retrospect, our hospital blood gas machine did not check for Glucose which potentially contributed to the delay in diagnosis)

4. Diazoxide can cause refractory (reversible) heart failure

5. Octreotide can still be effective in managing hypoglycaemia with Insulinoma despite negative Octreoscan