Use of Selective Arterial Calcium Stimulation Testing in Identification of Insulinoma in a Patient After Bariatric Surgery

Abstract

Objective Insulinomas are rare in the post-bariatric surgery setting. The differential diagnosis for hypoglycemia is broad, requiring laboratory testing to verify endogenous hyperinsulinemic hypoglycemia. Selective arterial calcium stimulation testing (SACST) can help localize abnormal insulin production. We describe a patient with histologically confirmed insulinoma after bariatric surgery diagnosed with the aid of SACST. Methods We present a 67 year old woman with a history of Roux-en-Y bypass surgery who presented with endogenous hyperinsulinemic hypoglycemia. Initially, no pancreatic lesion was identified radiologically. We pursued SACST to localize the source of insulin production. Results The SACST successfully localized the source of hyperfunctioning islet cells to the pancreatic tail with absolute insulin values in a range consistent with insulinoma. Additional radiologic studies showed a small tumor in the pancreatic tail. Pathology showed a well-differentiated neuroendocrine tumor, compatible with insulinoma. Conclusion This case study illustrates the usefulness of SACST for the diagnosis and localization of insulinoma.

Insulinoma After Bariatric Surgery: Tricks for Diagnosis and Therapeutic Approach

“…Insulin resistance caused by the obesity as well as lack of awareness of symptoms of hypoglycemia by the patients, may contribute to the delay in the identification of the insulinoma. Patients often fail to recognize autonomic warning symptoms and the hypoglycemia is only detected through the presence of neuroglycopenic symptoms delaying the diagnosis of the insulinoma for up to 5 years [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37].…”