Single luteal phase serum progesterone assay as an indicator of ovulation

A study was undertaken to determine whether solitary progesterone as says performed on serum samples obtained in the midluteal phase would provide the clinician with a convenient indicator that ovulation had occurred in that cycle. After a normal luteal-phase range was establish ed, single luteal-phase serum progesterone sampling was performed in 51 infertile women with regular menses and 35 oligomenorrheic women undergoing clomiphene citrate therapy. In the follicular phase of the cycle, progesterone levels were consistently less than 2 ng/ml. Between 11 and 4 days prior to the onset of menses in presumptively ovulatory cycles, serum progesterone levels were always 3 ng/ml or greater. Progesterone values in this range were always accompanied by a secretory endometrium and can be considered presumptive evidence of ovulation. This rapid, easily performed technique enables 1 technician to assay 30 or more samples for progesterone in a single working day and the results are available within 24 hours. This assay technique is easier to perform and more reproducible than a urinary pregnanediol assay, and it is expected that clinical laboratories will soon perform serum progesterone assays as a routine procedure.