Endocrine Abstracts

A 69-year-old non-diabetic woman presented with 1 month of recurrent drowsiness and confusion secondary to hypoglycaemia, nocturnal and on fasting. On admission her CBG was 2.6 mmol/l, confirmed venously. Her history was of a large solitary fibrous tumour (SFT) of the chest wall first resected in 2011 with recurrent relapses requiring surgery in 2016 and 2017. Histology showed typical features of SFT. Despite palliative chemo-radiotherapy for a further relapses, there was progression. By December 2020, disease was within the pleura with paratracheal deposits and a poor predicted prognosis. A normal short synacthen test ruled out adrenal insufficiency. Insulin (12 pmol/l) and C-peptide (<94 pmol/l) levels were appropriate for the level of hypoglycaemia (2.5 mmol/l). Overnight enteral feeding was started, given the burden of nocturnal hypoglycaemia, which improved on discharge. However, she was re-admitted 2 months later with severe daytime hypoglycaemia and a paraneoplastic cause was sought. Insulin-like Growth factor I (IGF-I) levels (6.3 nmol/l) and IGF-II levels (149 nmol/l) with an IGF-I: IGF-II ratio of 23.7 (normal<10) were consistent with a diagnosis of non-islet cell tumour hypoglycaemia, i.e. Doeger-Potter syndrome. This is a paraneoplastic syndrome characterised by ectopic secretion of IGF-II from a SFT leading to hypoinsulinaemic hypoglycaemia. Histologically proven SFT, hypoglycaemia excluding other causes and raised IGF-II:I ratio met the criteria for diagnosis. We started 40 mg prednisolone daily with resolution of hypoglycaemia. We then introduced growth hormone (GH) (somatotropin 0.4 mg) once daily and slowly titrated up to maximum tolerated dose and the steroid weaned down. The result has been excellent with no hypoglycaemic events since discharge 1 month ago. Doeger-Potter syndrome is rare cause of hypoglycaemia but speedy diagnosis and effective steroid and GH treatment have allowed our patient to spend valuable time with family in this terminal period.