Development and application of a radioimmunoassay for plasma glucagon.

We report sensitive radioimmunoassay procedures for glucagon-like immunoreactivity and for pancreatic glucagon, with use of antisera generated in rabbits by the injection of glucagon covalently coupled to thyroglobulin. Optimum assay conditions were determined. These assays have absolute limits of sensitivity of 10 to 20 pg, an intra-assay coefficient of variation of 8%, and an inter-assay coefficient of variation of up to 22%. In human infants 30 minutes after birth, glucagon concentration was 227 ± 27 pg/mI (SEM), and glucagon-like immunoreactivity increased sharply with oral feeding. In children and adolescents, plasma glucagon concentrations during fasting, the increase in response to arginine stimulation, and the suppression after oral glucose loading were similar to values previously reported in adults. Problems inherent in the methodology for measuring plasma glucagon are discussed.