Insulin-like growth factors in patients with nonislet cell tumors and hypoglycemia

• Published in: Metabolism, clinical and experimental Vol. 35; no. 4; p. 360
• Main Author: Merimee, T J
• Format: Journal Article
• Language: English
• Published: United States 01.04.1986
• Subjects: Arginine - pharmacology; Carrier Proteins - analysis; Humans; Hypoglycemia - blood; Insulin-Like Growth Factor Binding Proteins; Insulin-Like Growth Factor I - blood; Insulin-Like Growth Factor II - blood; Neoplasms - blood; Receptors, Cell Surface - analysis; Receptors, Somatomedin; Somatomedins - blood
• ISSN: 0026-0495
• DOI: 10.1016/0026-0495(86)90155-1

Insulin-like growth factors (IGF) in serum from 3 patients with nonislet cell tumors and hypoglycemia were measured by radioimmunoassay and by means of a rat liver membrane assay (specific for IGF II). The concentration of IGF II by receptor assay was greater than normal when the samples were initially assayed, but subsequently decreased 48% to 80% over the next 8 to 15 weeks. In the same serum samples, concentrations of both IGF I and IGF II by radioimmunoassay were consistently less than normal. In all 3 patients growth hormone (GH) responses to intravenous arginine were depressed and in 2 of the 3 patients, a GH-dependent 150 K serum protein carrier of IGF was absent. None of these abnormalities were seen in 7 patients with insulinomas and chronic hypoglycemia. The data suggest that some patients with nonislet cell tumors and hypoglycemia produce a receptor-active, nonimmunoreactive IGF-II-like material. This material appears (a) more labile than normal IGF II and (b) capable of inhibiting GH secretion. The latter effect may decrease immunoreactive IGF I and II, as well as decrease the GH-dependent 150 K protein carrier of these factors. The extreme lability of the IGF-II-like material produced by tumors probably explains the previous contradictory reports on this topic.