Radioimmunoassay of Group I Pepsinogens (PG I) and the Effect of Food on Serum PG I

Abstract

A sensitive and precise radioimmunoassay of group I pepsinogens (PG I) 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 PG I 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 PG I. Serum PG I in 388 non-fasting subjects 20–49 years old was 164 ± 5 ng/ml (mean ± S.E.M.). In these subjects serum PG I was significantly higher in men than in women. In both sexes the frequency distribution showed two peaks, indicating the presence of two different populations.