In healthy adults, hyperinsulinaemic hypoglycaemia is rare and therefore needs further investigation. Such a state invariably indicates endogenous insulin secretion after a careful history has ruled out Sulphonylurea abuse. Optimal diagnostic and management strategies remain a challenge. A recent observational study in a tertiary Centre in Cambridge has identified 29 cases over a 13-year period and has found great value of the 48-h fast in diagnosing insulinoma and Endoscopic Ultrasound in pre-surgery localisation of tumour.
Our patient is a 62-year-old otherwise fit and well handyman who initially presented with collapse with loss of consciousness leading to occipital fracture and contre-coup brain contusions. Diagnosis remained somewhat uncertain for 6 months when he was seen by Cardiologist and then Neurologist as outpatients. He re-presented with difficulty in rousing in the morning after drinking whisky and lager at night without food. Capillary glucose of 1.4 was noted by ambulance crew. GP review after 4 days with capillary glucose 2.0 with no symptoms and admitted under medicine.
Capillary glucose of 1.9 at 0515 following admission to the Acute Medical Unit at 2,200 prompted blood sampling for glucose, insulin and C-Peptide. Glucose was 2.4 mmol/l, insulin 5.6 mU/l and C-Peptide 1,010 pmol/l. A second lot a few days later on the ward yielded glucose 2.4 mmol/l, insulin 10.3 mU/l and C-Peptide 1,288 pmol/l. Although a 0900 h Cortisol was 175, a Short Synacthen Test showed a good cortisol response. Other hormones including gut hormones were normal. CT and MRI Pancreas showed complete fatty replacement of Pancreas except for head and uncinate process and two small indeterminate nodules adjacent to spleen. Octreotide scan has shown no octreotide-avid focus involving the pancreas nor any octreotide avid disease elsewhere. Endoscopic Ultrasound has not shown any lesion. Since starting on Diazoxide 100 mg BD, there have been no hypoglycaemic episodes so far.
This is case is still posing great challenges with regards to the cause of hypoglycaemia despite biochemical confirmation with high insulin, C-Peptide with laboratory glucose of 2.4 mmol/l. The patient has now been referred to a Tertiary Centre and a Selective Arterial Calcium Stimulation with hepatic venous sampling is planned. Differential diagnoses remain as Insulin Autoimmune Syndrome or occult Insulinoma.
16 - 18 Apr 2018
Society for Endocrinology