Endocrine Abstracts

Introduction: Insulinoma is a rare tumor of the beta cells of the pancreas. The clinical manifestation is diverse with hypoglycemia and autonomic neurological symptoms. For diagnosis the Whipple’s triad needs to be present: signs of hypoglycemia, glucose level under 3 mmol/l and the cessation of symptoms after administration of iv. glucose. The fasting test confirms the diagnosis. The most commonly used imaging techniques that may localize the tumor are the abdominal ultrasound and CT scan; however, in some cases further procedures are necessary.

Case report: A 27 years old male patient without any other significant disease in his history presented with symptoms lasting for one year involving dizziness, fatigue, confusion, sweating and tremor. Blood glucose under 2 mmol/l was found on multiple occasions while presenting specific symptoms, which ceased every time after administration of iv. glucose. During the fasting test a low glucose level with consecutively elevated insulin and C-peptide levels were measured. In order to localize the tumor different imaging techniques were performed. Abdominal sonography, endoscopic ultrasound and spiral CT couldn’t find the suspected pancreatic tumor. Finally selective arterial angiography was performed with Ca-stimulation. After selective catheterization of the arteria lienalis, mesenterica superior and gastroduodenalis Ca--stimulation was performed. After administration of iv. calcium blood samples were collected from the right hepatic vein after 0.30 and 60 seconds. During the stimulation administered in the a. lienalis the 1-minute sample showed a significant rise in the insulin and C-peptide levels while after performing the stimulation on the other two arteries no remarkable differences were noticed. The concomitant arteriography showed a small, 1 cm diameter hyper vascularized nodule, characteristic for insulinoma.

Discussion: After establishing the diagnosis, the precise localization of the tumor within the pancreas can become a serious problem. According to the literature 10–27% of the insulinomas cannot be evidenced by the available imaging techniques. The selective Ca-stimulation technique can shrink the possible tumor localization to the region of the pancreas that is supplied with blood by the specific catheterized artery. With this procedure the majority of the pancreas can be saved. Although newer techniques, like GLP1 scintigraphy or sensitive intraoperative ultrasound became available recently, the selective Ca-stimulation can still be used for the identification of insulinomas non-detectable by less expensive noninvasive methods.