Endocrine Abstracts

A 72 year old man was admitted with chest-pains and leg and abdominal swelling and was diagnosed with significant coronary artery disease. He was incidentally noted by nursing staff to have episodes of irritability and drowsiness associated with low capillary glucose. His lowest laboratory blood glucose was 1.8mmol/L which was contemporaneous with signs rather than symptoms of hypoglycaemia. Resolution of signs was prompt when glucose normalized thus fulfilling Whipple’s triad. Abdominal ultrasound demonstrated a large abdominal mass confirmed with CT with the mass connected to the retroperitoneum, pancreas, stomach and mesentery. Blood testing associated with laboratory glucose <2mmol/L were as follows: insulin <3.0mU/l, C-peptide 1.1ug/L and 3-OHbutyrate <0.1mmol/l. Urinary sulphonylurea screen was negative. Samples analyzed by Royal Surrey peptide lab were as follows: IgF1 8.9nmol/l (5-25nmol/l), IGFBP-3 2.1 mg/L (2.6-6.3 mg/l). IGF-2 199.3nmol/l and IgF2:IGF1 ratio 22.4 (<10). His hypoglycaemia became more frequent requiring hospital readmission. He was given a sensor for CGM, with hypoglycaemia alarm set at 4.5mmol/L and connected to remote access. He had coronary artery bypass grafting followed by open abdominal surgery and his hypoglycaemia resolved post operatively. Histopathology was of a 21x20x15 cm lesion weighing 3.5 Kg, composed of spindle cells, consistent with a fibrous tumour. Mitotic count was 2/10 HPF, margins were not clear (R1) and the lesion was classified as high (~70%) risk for metastasizing. IGF2 is secreted by mesenchymal and epithelial tissues, and associated with fibrous tumours causing hypoglycaemia and suppressed IGF1, growth hormone and insulin. His prescription for CGM was outside of NICE guidelines but this has facilitated his outpatient followup especially given his hypoglycaemic unawareness. Lack of hypoglycaemic awareness at presentation is a characteristic feature of such tumours (both islet-cell and non-islet cell) and so there may be a niche but important role for CGM in management of these complex cases.