Endocrine Abstracts

A 79-year-old female patient, with a background history of hypertension and ischaemic heart disease was brought by ambulance to hospital with near collapse episode associated with capillary blood glucose (CBG) of 2.1 mmol/l. Her regular medications include Ramipril, clopidogrel and atorvastatin. She had no history of diabetes. While inpatient, it was observed that majority of low capillary blood glucose readings (CBG) were late night or early mornings. At venous glucose of 1.9 mmol/l, C peptide was found to be <94 pmol/l and serum insulin <10 pmol/l pointing towards non-islet cell hypoglycaemia. She has normal hypothalamic pituitary adrenal (HPA) axis. Further investigations revealed insulin like growth factor-2 (IGF-2) value of 79.5 nmol/l with Serum insulin like growth factor-1 (IGF-1)- 3.6 nmol/l (4.4–21.8) and serum insulin like growth factor binding proteins (IGFBP3) of 2.2 mg/l (2.0-5.5). IGF-2: IGF-1 ratio was significantly high at 22.1 suggesting diagnosis of insulin like growth factor 2 (IGF-2) driven non islet cell hypoglycaemia. CT abdomen and pelvis with contrast showed an 18 cm lobulated inhomogeneous pelvic mass with multiple liver masses. There was filling defect within the inferior vena cava extending into the left common iliac vein in keeping with venous thrombosis. Subsequent tissue biopsy confirmed a diagnosis of gastro-intestinal stromal tumour with paraneoplastic IGF2 driven hypoglycaemia. Hypoglycaemia treated initially with prednisolone showed little improvement. Later she was switched to dexamethasone with good response. Unfortunately patient developed retroperitoneal bleed secondary to treatment dose enoxaparin for inferior vena cava thrombosis and passed away within 8 weeks of her diagnosis. Non islet cell tumour hypoglycaemia (NICTH) is a rare but serious complication of malignancy characterised by tumoral overproduction of incompletely processed IGF-2, which results in stimulation of insulin receptors and increased glucose utilization.