Endocrine Abstracts

Introduction

Insulinoma is the most frequent endocrine tumor of the pancreas and a diagnosis challenge in all cases of spontaneous hypoglycemia. The confirmation of hypoglycemia is the first step of the diagnosis before initiating the complementary investigations to confirm the insulinoma and determine its localization. The aim of this study was to investigate the diagnosis of insulinoma in a setting of organic hypoglycemia.

Methods

We performed a retrospective study of 38 adults in patients presenting with spontaneous hypoglycemia over a 19-year period. Hypoglycemia was confirmed when blood glucose levels were inferior to 0.45 g/l, insulinemia and C-peptide were elevated if respectively superior to 3 µUI/ml and 0.6 ng/ml.

Results

Ten patients were included with a confirmed hyperinsulinic hypoglycemia, with a sex ratio of 3/7. The mean age was 41 ± 15 years. Neurogenic and neuroglycopenic symptoms were present respectively in 9 and all cases. Fasting hypoglycemia was present in 6 cases, after physical activity in one case and at any time in 3 cases. Hypoglycemia was obtained spontaneously in 6 cases with mean hypoglycemia at 0.27 g/l, mean insulinemia at 118.6 µUI/ml and mean C-peptide at 32.01 ng/ml. Hypoglycemia was obtained after a supervised fast test in 4 cases, with hypoglycemia obtained after a mean of 3 hours. Mean hypoglycemia was 0.28 g/l, mean insulinemia was 29.8 µUI/ml and mean C-peptide was 5.13 ng/ml. Sulfonylureas weren’t detected in all patients. In imaging investigations, abdominal ultrasonography was normal in the 6 patients it was performed on. Abdominal CT scan was performed in 8 patients and found a tumor in 3 cases. Abdominal MRI was performed in 7 patients, was normal in 3 cases and found a tumor in 4 cases. Endoscopic ultrasound was performed in 8 patients, was normal in 3 cases and found a tumor in 5 cases. It found a tumor in the 4 patients with a tumor in the MRI with a patient whose tumor was only diagnosed with endoscopic ultrasound. The tumors confirmed by CT scan weren’t found by other imaging means. CT scan and endoscopic ultrasound were enough to found the localization in the 8 patients with confirmed localization before surgery.

Conclusion

The diagnosis of insulinoma is easily confirmed when the hypoglycemia is confirmed and allowing all biology investigations. The challenge remains in the localization as no imaging procedure was enough on its own to confirm localization, and even with all procedures, localization wasn’t found in 2 cases, confirming therefore the difficulty of pre-operative investigations.