Abstract
A 50-year-old man was admitted with spontaneous hypoglycemia and retroperitoneal mesothelioma. As his fasting plasma IRI level was low, he was diagnosed as having non-islet-cell tumor hypoglycemia (NICTH)
He had a high blood concentration of insulin-like growth factor II (IGF-II), with an increase in the percentage of the large molecular weight form, as well as altered blood IGF II-IGF binding protein formation. His plasma IGF-I was also low.Before tumorectomy, three types of insulin-secretion test were conducted. On the i. v. glucose loading test, the early phase of the insulin response was almost intact, but the later phase showed gradual suppression. On the oral glucose test, secretion was grossly suppressed. On the i. v. glucagon test, the response was completely suppressed. After tumorectomy, all of the above humoral factors and the results of the three tests returned to normal.
These data suggest that heterogenous IGF-II is produced and that IGF binding proteins are altered in patients with NICTH. It was also noteworthy that, in the same patient, intrinsic insulin and its secretion were suppressed with variable responses to three different stimulations. These observations led us speculate that some unknown substance related to appropriate insulin suppression is involved, in an undefined way, in the pathogenesis of NICTH and the role of IGF-II.
