[Recently experienced ten cases of insulinoma--preoperative diagnosis of localization and intraoperative simultaneous monitoring of glucose and insulin].

We have experienced 10 cases of insulinoma during the last 10 years from 1977 to 1986. All cases had strong hypoglycemic symptoms such as disturbance of consciousness, and insulinoma still tended to be misdiagnosed as epilepsy. The diagnosis of insulinoma was easily available from serum IRI (immunoreactive insulin)/plasma glucose ratio in all of the ten cases. As preoperative procedures for the diagnosis of localization, arteriography, computed tomography and portal blood sampling were positive in 6 of 8, 4 of 6 and 2 of 2 patients, respectively. At operation, all insulinomas could be identified by digital palpation. We performed simple excision of the tumor in 6 patients and distal pancreatectomy in 4 patients. The tumors were solitary and benign in all patients, ranging in size from 1.0 cm to 4.5 cm. Three cases were presented as case reports. In these cases, portal blood sampling and/or intraoperative monitoring of plasma glucose and serum IRI were performed. Portal blood sampling was effective even for a case which was negative in image diagnostic procedures. Furthermore, simultaneous monitoring of plasma glucose and serum IRI by quick radioimmunoassay seemed to be a good guide to the completeness of resection of insulin producing tumors.