A 51-year-old female presented with a 9 month history of symptoms suggestive of hypoglycaemia and associated episodes of unconsciousness, which were prevented by frequent food intake but with subsequent weight gain. She reported a history of lactose-induced anaphylaxis and the use of lactose-free subcutaneous prednisolone since sustaining a traumatic cardiac injury in 1987.
Two supervised prolonged fasts demonstrated hypoglycaemia with elevated insulin levels. C-peptide was detectable but below the reference range (Table). The cortisol level was 759 pmol/l. The 24 h urine collection did not detect sulphonylurea. CT and MRI scans showed normal pancreatic appearances. An octreotide scan was also normal.
Selective arterial catheterisation with calcium gluconate stimulation showed a flat insulin response in: the hepatic; gastroduodenal; distal, mid and proximal splenic and superior mesenteric arteries (glucose 2.44.6 mmol/l, insulin 48.257.1 mU/l). Therefore no abnormal pancreatic region was localised.
Further discussions with the laboratory confirmed that the ratio of insulin to C-peptide was not consistent with an insulinoma. It subsequently transpired that the subcutaneous prednisolone was not obtained from any healthcare practitioner. To determine whether this was a source of exogenous insulin we offered an alternative oral, lactose-free preparation of prednisolone which she declined. It is understood that she is currently under investigation for criminal activities. It is postulated that she presented with factitious hypoglycaemia in order to avoid a custodial sentence and is undergoing psychiatric evaluation.
Determining the cause of hypoglycaemia amongst the many possible differential diagnoses can be difficult, and a systematic approach is necessary. This may have a significant medico-legal bearing, which our case illustrates. Psychiatric evaluation is recommended for the management of factitious hypoglycaemia.
|C-peptide (2651324 pmol/l)||128||142|
|Insulin (4.426.0 mU/l)||126||50.7|
|Pro-insulin (07 pmol/l)||2.0|