An 87 year old man was referred to our endocrine service from the medicine for the elderly team for investigation of suspected hypoglycaemia. He had several co-morbidities but did not have diabetes mellitus. There was a 6 month history of funny episodes characterised by lethargy, profuse sweating and confusion. The symptoms resolved a few minutes after eating. One such episode occurred while attending his GP who arranged for blood to be drawn. The plasma glucose was 1.9 mmol/l hence satisfying Whipples triad. A CT chest, abdomen and pelvis performed prior to referral to investigate unexplained weight loss revealed an endoluminal lesion in the bladder thought to represent a localised tumour as well as pleural thickening (secondary to asbestos exposure) and a possible small left sided empyema. Considering the patients relative frailty and already proven hypoglycaemia, it was decided to arrange an immediate inpatient stay on our ward to complete the necessary investigations. A short Synacthen test showed a peak cortisol of 1008 nmol/l thereby excluding adrenal insufficiency. A few hours into an overnight fast he became hypoglycaemic and blood drawn at the time demonstrated hyperinsulinaemic hypoglycaemia plasma glucose 1.8 mmol/l, insulin 36 mU/l (ref. range 317) and c-peptide 3.19 nmol/l (0.361.12). The sample was delayed in reaching the laboratory for at least a few hours which may have led to degradation of insulin and c-peptide prior to analysis. The elevated results, however, still supported a diagnosis of endogenous insulin excess. The respiratory physicians reviewed his radiology and attempted an US-guided pleural aspiration but the tap was dry. The patient was followed up as an outpatient thereafter. A follow-up CT scan showed no change in the thorax but did reveal a 13 mm rounded lesion in the tail of the pancreas possibly representative of a small insulinoma. Investigation by our urology colleagues confirmed a high-grade transitional cell carcinoma of the bladder. This was successfully treated with intravesical BCG immunotherapy. Due to the patients frailty and wish not to undergo surgery, the hypoglycaemia has been successfully managed with diazoxide alone. This case demonstrates a (probable) insulinoma in an elderly patient presenting with spontaneous hypoglycaemia. Insulinoma has been described at the extremes of age and cannot be thought of exclusively as a condition of middle age. The case also highlights the need to investigate and manage patients taking into account their own wishes and co-morbid state.
16 - 18 Apr 2018
Society for Endocrinology