[Determining progesterone in saliva]

A radioimmunoassay for the determination of progesterone in saliva using a 125J-labelled progesterone derivate has been developed. The assay is characterized by the excellent sensitivity of 3.12 pg progesterone/ml. During the menstrual cycle of normal women the biphasic rhythm of progesterone in saliva could not been clearly demonstrated. In the follicle phase high peaks of progesterone have been shown and even in the luteal phase individual low values have been observed. The circadian rhythms of progesterone in saliva are characterized by irregular oscillations. The saliva flow rate is not responsible for the progesterone concentration. The measurement of progesterone in serum seems to be more useful in the diagnosis of sterility.