Evaluation of the operative parameters for a human prolactin radioimmunoassay in serum

A sensitive homologous radioimmunoassay (RIA) for human prolactin (hPRL) was evaluated. The experimental parameters of this double antibody solid phase (DASP)-hPRL-RIA are discribed. The RIA measures concentrations of hPRL as low as 1 ng/ml of human serum and allows repetitive measurements and accurate delineation of serum hPRL. The assay is specific for hRPL; only HGH shows a weak cross-reaction. The antigen recovery tests are quantitative. The serum concentrations of hPRL in a group of randomly selected male and female individuals averaged 6.7 +/- 3.3 ng/ml, respectively. In a chronobiological study performed on 21 subjects (5 male and 16 female), a statistically significant rhythm with a 24-h period was detected.