24-hour profiles of salivary progesterone

To assess whether the known pulsatility of P secretion by the corpus luteum, which is detected in blood by P measurements, translates into fluctuations of saliva P concentrations, and to determine how well saliva P measurements reflect plasma P concentration. A second objective was to see whether there is a window in the luteal phase, where P secretion has reached its maximum capacity, but the amplitude is not very accentuated, which would be an ideal time to measure P.

Twenty-one ovulatory women were randomly assigned to be studied on day 5, 7, or 8 after the luteinizing hormone surge. Blood samples were drawn every 20 minutes, and saliva samples were obtained hourly over a 24-hour period. Comparison between saliva plasma P was performed, and pulse analysis of plasma P was done.

The percent variation of saliva P concentration over a 24-hour period was much higher when compared with the percent variation of plasma P concentration over the same time period (saliva P: 149%; plasma P: 107%). Also, the ratio of saliva to plasma P varied significantly between individuals (range: 0.0050 to 0.0148). A single plasma P concentration (8:00 A.M.) correlated better with the 24-hour mean plasma concentration than the respective single saliva value or the mean of two or three saliva samples (8:00 A.M. and 12:00 P.M.; 8:00 A.M., 12:00 P.M., and 8:00 P.M.). Plasma pulse frequency, mean pulse interval, pulse width, pulse amplitude, and 24-hour mean P level did not differ between the 3 study days.

A single plasma P determination reflects more accurately 24-hour P secretion than repeated saliva P samples measured in the same individual. We could not identify a window in the luteal phase when P measurements are more representative of corpus luteum function.