THU522 Symptomatic Hypoglycemia As The First Manifestation Of Multiple Endocrine Neoplasia Type 1 (MEN-1): Case Report

Disclosure: V.D. Oliveira: None. S.C. Tormin: None. B.V. Dias: None. N. Scalissi: None. R.D. Scalco: None. C. Olivati: None. A. de Moricz: None. L.A. Szutan: None. J.V. Lima: None. Introduction: MEN-1 is a rare, autosomal dominant syndrome that occurs due to a pathogenic variant of MEN1. The incidence of insulinoma in MEN-1 is relatively rare. 4-6% of patients with insulinoma will develop MEN-1. Unlike sporadic insulinomas that usually develop after the age of 40, MEN-associated insulinoma usually occur before 40 years of age and even sometimes before 20. CASE REPORT: A 26-year-old male patient had a 3-year history of Whipple's triad associated with significant weight gain with a body mass index (BMI) of 33 kg/m² to 58 kg/m² during this period. His father has a metastatic carcinoid tumor, being treated with palliative chemotherapy. Laboratory tests at the time of hypoglycemia were: blood glucose 42mg/dL (RV 75-99), insulin 39 mU/L (RV < 3) and C-peptide 11.6 ng/dL (RV < 0.2). Magnetic resonance imaging (MRI) of pancreas showed 3 hypervascular nodules, the largest in the tail, measuring 3.3 cm, with neuroendocrine characteristics. Distal pancreatectomy, splenectomy and lymphadenectomy were indicated. After surgery, the episodes of hypoglycemia disappeared, with a weight loss of 25 kg. He required postoperative metformin, with satisfactory glycemic control. During the investigation, a prolactinoma was diagnosed (pituitary MRI, which showed a 4 mm adenoma, prolactin 56ng/mL (LR < 25) and hypogonadotrophic hypogonadism), and cabergoline 0.25 mg/week was started. In addition, diagnosis of mild primary hyperparathyroidism (PTH 188 pg/mL and calcium 10.4mg/dL). Parathyroid scintigraphy with 99mTc-MIBI showed increased uptake in the right lower parathyroid. Genetic testing was performed by Next Generation Sequence (NGS) of the MEN1 gene, which was positive for the pathogenic variant c.825-2A>G in heterozygosis in intron 5. A molecular study was performed on the patient's father and sister, which identified the same pathogenic allelic variant in both. Conclusion: We described a rare case of MEN-1 whose first manifestation was insulinoma. Presentation: Thursday, June 15, 2023