Radioimmunoassay of group I pepsinogens (PGI) and the effect of food on serum PGI.

A sensitive and precise radioimmunoassay of group I pepsinogens (PGI) in serum is described. The method is a modification of the one described by Samloff and Liebman. The most important improvement is that 125I-labeled PGI can be stored diluted for at least 7 weeks without loss of immunoreactivity. The present method has a detection limit of 2.6 ng/ml, a within-assay precision of 6%, and a between-assay precision of 17% in the normal range. A light test meal had no significant effect on serum PGI. Serum PGI in 388 non-fasting subjects 20-49 years old was 164 +/- 5 ng/ml (mean +/- S.E.M.). In these subjects serum PGI was significantly higher in men than in women. In both sexes the frequency distribution showed two peaks, indicating the presence of two different populations.