NSILA-s is an insulin-like peptide which reacts with its own receptor and the insulin receptor. NSILA-s is elevated in about 40 percent of patients with hypoglycemia and non-islet cell tumors. Extracts of the tumor contain the peptide suggesting ectopic production. NSILA-s is low in hypopituitary doses of growth hormone (GH), however, NSILA-s does not appear to respond acutely to changes in endogenous GH. Relaxin, another peptide with structural similarities to insulin, does not react with the insulin receptor or the NSILA-s receptor. BIBLIOGRAPHIC REFERENCES: Megyesi, K., Kahn, C.R., Roth, J., and Gorden, P.: Physiology of Non-suppressible Insulin-like Activity. In: Endocrinology, Volume 2, Proceedings of the V International Congress of Endocrinology, Excerpta Medica, Amsterdam-Oxford, 1977, pp. 173-177. Hyodo, T., Megyesi, K., Kahn, C.R., McLean, J.P., and Friesen, H.G.: Adrenocortical Carcinoma and Hypoglycemia: Evidence for Ectopic Production of Non-suppressible Insulin-like Activity by the Tumor. J. Clin. Endocrinol. Metab., 44, 1175-1184, 1977.