Radioimmunoassay of progesterone in saliva

A rapid specific radioimmunoassay for progesterone in mixed, unstimulated saliva is described. Column chromatography is not necessary. One single extraction with petroleum ether provides a fractional recovery of 75-95%. The assay sensitivity is 9 pg progesterone/tube. The intra- and interassay variation for low, medium, and highly concentrated progesterone pools is 13.1-9.5 and 17.4-13.9%, respectively. Analytical recovery documents excellent correlation between expected and detected progesterone concentrations (r = 0.994). Data from salivary progesterone of a regularly menstruating girl and of a patient with XO Turner's syndrome are provided.