FRI668 Insulinoma As A Cause Of New Onset Hypoglycemic Episodes
Authors: Zahra Sundas , Abbas Mubashir A , Subramani Rashmi , Manas F N U , Yavuz Sahzene 
Published: October 2023

Disclosure: S. Zahra: None. M.A. Abbas: None. R. Subramani: None. F. Manas: None. S. Yavuz: None.

37 years old female with a past medical history of hypothyroidism presented with complaints of shakiness, lightheadedness, and palpitations, relieved by eating. The physical examination was unremarkable. Fasting blood work showed low glucose of 41 mg/dl (70-99 mg/dl), normal insulin levels of 8.4 UIU/ ml (normal:1.9-23 UIU/ml), elevated proinsulin 21.1 pmol/ L (normal:&lt;8.0 pmol/L), normal C Peptide 2.5 ng/ ml (normal:1.1-4.4 ng/ml), and negative for insulin antibody. Serum ACTH and cortisol levels were normal. Blood testing for hypoglycemia-inducing medications was negative. CT and MRI abdomen pelvis contrast was normal. She was prescribed to wear Dexcom to monitor her blood glucose round the clock. She continued to have low blood glucose, sometimes without symptoms and was rescued by the alarm. She underwent endoscopic ultrasound and was found to have a 10mm x 9mm ill-defined rounded pancreatic head mass with diffuse echogenicity of the pancreas. Biopsy of the mass revealed clusters of epithelial cells with neuroendocrine differentiation, compatible with insulinoma. She underwent surgical resection of the mass. She was also referred to genetic testing due to the association of pancreatic tumors with MEN syndrome. The diagnosis of Insulinomas is clinical as well as biochemical with presenting symptoms of Whipple’s Triad along with the presence of the following lab findings: hypoglycemia with plasma glucose of less than 50mg /dl, insulin greater than 5 UIU/L, C-Peptide greater than 0.2 nmol/L (0.6 ng/mL), Insulin/C-Peptide ratio of greater than 1.0, Proinsulin greater than 20pmol/L, and the absence of sulfonylurea metabolites in plasma or urine. Insulinoma is the most common pancreatic neuroendocrine and functional endocrine tumor of the beta cells of the pancreas with a prevalence of 1-4 people per million with equal gender distribution. They are mainly seen in the fifth decade of life but can occur at any age. They can occur sporadically or can be associated with MEN 1. Insulinomas are mostly benign, about 5-10% can be malignant. When to do medical vs surgical management? For benign insulinomas, surgical resection is preferred. For locally invasive and malignant tumors, aggressive surgical resection is performed, unless surgery is contraindicated for any other reason or patient refuses it. Medical treatment is reserved for the patients with diffuse Beta cell disease, multiple insulinoma and unresected malignant insulinoma. In the presence of unresectable metastatic disease; radiofrequency ablation, selective embolization, intraarterial chemotherapy, alone or in combination has been shown to be effective in controlling hypoglycemic episodes and improving quality of life. Octreotide, via inhibiting insulin secretion, normalizes the blood glucose levels. For better detection of hypoglycemia and adequate response to medical therapy, continuous glucose monitoring is helpful.

Presentation: Friday, June 16, 2023