PSUN286 A Rare Case of Non-Islet Cell Tumor Hypoglycemia in Young Female With Metastatic Neuroendocrine Tumor

BACKGROUND: Non-islet cell tumor hypoglycemia (NICTH) is a rare paraneoplastic syndrome caused by a benign or cancerous tumor that over-secretes various hormones that lead to hypoglycemia. Multiple etiologies were described in literature, the most common of them is abnormal secretion of insulin-like growth factor-2 (IGF-2) known as Doege-Potter syndrome (first described in 1929). Other etiologies include oversecretion of proinsulin, IGF-1, and somatostatin. Estimated incidence of NICTH is one per one million person-years. Tumors of mesenchymal origin are most often described in association with NICTH. Laboratory diagnosis of fasting hypoglycemia associated with serum insulin levels below 3 μU/ml confirm the diagnosis of NICTH. In the case of Doege-Potter syndrome, lab findings show low levels of insulin, c-peptide, IGF-1 and a high IGF-2: IGF-1 ratio, which indicate non-insulin-mediated hypoglycemia due to IGF-2 oversecretion. Neuroendocrine tumors presented with NICTH are rare and only described in several case reports. CLINICAL CASE: We report a case of a 34 year old female with metastatic neuroendocrine high grade tumor (WHO grade 3, non small cell, diagnosed 3 years prior to presentation) with metastasis to the bone (status post debulking and radiation) and brain (status post radiation therapy). Patient was admitted due to left ankle cellulitis. Endocrinology was consulted due to incidental finding of hypoglycemia serum glucose of 44 mg/dL. Repeat serum levels showed c-peptide 1 ng/dL (normal 1.1 - 4.4) and glucose of 54 mg/dL. She denied a history of diabetes mellitus, alcohol intake, insulin or sulfonylurea use. She had normal renal and liver function. Continuous infusion of D10 started and after 24 hours the patient's hypoglycemia improved. However, hypoglycemia recurred every morning. Following morning hypoglycemia repeat serum labs showed insulin 1.3 (Normal 2.6-24.9), c-peptide 0.9 ng/dL, and serum glucose of 114 mg/dL confirming that her hypoglycemia was not insulin induced. She was not on any medications known to cause hypoglycemia. CT abdomen without contrast showed left upper quadrant heterogeneous hypoattenuating mass with calcifications, measuring approximately 8.5 cm×10.1 cm×2.6 cm. CONCLUSION: This is a case of a patient with a high grade non small cell metastatic neuroendocrine tumor who presented with NICTH. This is the first case of a neuroendocrine tumor with non-small cell pathology causing NICTH that has been described to-date. Based on the patient's clinical presentation and available laboratory findings with recurrent fasting hypoglycemia, low insulin and c-peptide levels we confirmed diagnosis of NICTH. This patient`s hypoglycemia was most likely induced by IGF-2 overexpression (Doege-Potter syndrome) which is the most common cause of NICTH. Presentation: Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m.