Endocrine Abstracts

Introduction: Nonislet cell tumour hypoglycemia (NICTH) is a rare complication of malignancy. The most common cause is overproduction of IGF2, which activates insulin receptors, resulting in hypoinsulinemic hypoglycemia. When a solitary fibrous tumor is responsible, it is called Doege-Potter syndrome.

Case 1: 58-year-old woman, with a history of gastrointestinal stromal tumor and pleural solitary fibrous tumor with pulmonary and lymph node metastases. She presented in the ER with altered mental state and hypoglycemia (minimum glucose value of 32mg/dl). Bloodwork showed: glucose 34 (76-115) mg/dl, C peptide 0.294 (1.1-5.0) ng/ml and insulin <0.400 (2.6-24) uUI/ml. The patient was started on therapy with corticosteroids and was later discharged with prednisolone 60mg daily. Further bloodwork showing IGF2 639 (230-970) ng/ml and IGF1 20.3 (63.3-190) ng/ml, with an IGF2/IGF1 ratio of 31.5 (>10) confirmed the diagnosis of Doege-Potter syndrome. The patient improved significantly after treatment with chemotherapy, with progressive tapering of prednisolone.

Case 2: 55-year-old man, with a history of diabetes mellitus type 2. He was admitted after he presented in the ER with acute confusional state in the context of hypoglycemia (minimum glucose value of 25mg/dl). Physical examination showed an abdominal mass. An abdominal MR confirmed the presence of an abdominopelvic mass, with 27x13cm, and a biopsy was performed, suggestive of lipossarcoma. Bloodwork showed: glucose 58 (76-115) mg/dl, C peptide 0.10 (1.10 – 4.40) ng/ml, insulin <0.40 (2.6-24.9) U/ml and IGF1 30.1 (67.0-195) ng/ml. Due to a laboratorial mistake, IGF2 was not measured. However, after mass excision, bloodwork showed normal IGF1 [220 (67.0-195) ng/ml], C peptide [2.30 (1.1-5.0) ng/ml] and insulin [8.35 (2.6-24.9) uUI/ml] values, and so IGF2 tumor production was assumed. After surgery, no further hypoglycemia events were detected.

Conclusão: NICTH must be considered, even when IGF2 measurement isn’t possible, in the presence of low glucose values and suppressed C peptide/insulin and IGF1 values.