Non-insulinoma pancreatogeneous hypoglycemia syndrome (NIPHS) is a rare cause of hypoglycemia in adults. The cause of NIPHS is diffuse hyperinsulinism. As a result, computed tomography (CT) of pancreas, endoscopic pancreatic ultrasonography (EUS), and somatostatin receptor scintigraphy (SSRS), which are usually performed to locate an insulinoma, are not able to diagnose NIPHS. Moreover, SSRS can give a false-positive result. In this case report, we introduce a 22-year-old Thai woman who presented with fasting and postprandial hyperinsulinemic hypoglycemia. Accordingly, an insulinoma was suspected. She underwent several studies to locate the lesion. Pancreatic CT and EUS failed to locate a lesion; however, SSRS showed a faint focus of increased uptake at the pancreatic head. The suspected insulinoma was not identified during a first operation. Thereafter, other diagnostic methods were performed in an effort to locate the suspected insulinoma, including selective arterial calcium stimulation test. The result of the selective arterial calcium stimulation test was negative. Intraoperative ultrasonography during a second operation also failed to locate a tumor. Finally, a pancreatic head resection was performed according to SSRS result, yet capillary blood glucose levels did not increase after resection. In response, a 95% pancreatectomy was performed. The pathology report was consistent with diffuse hyperinsulinism. This report emphasizes that SSRS can give false positive result in NIPHS.

Keywords: Hypoglycemia, Insulinoma, Non-insulinoma pancreatogeneous hypoglycemia syndrome, Somatostatin receptor scintigraphy