Progesterone
Progesterone is a steroid hormone synthesized from cholesterol and is important as an intermediate in the pathway to cortisol via pregnenolone, estrogens and testosterone. Progesterone induces the cyclic changes in the endometrium that allow implantation of the fertilized ovum. Progesterone is also responsible for maintenance of the uterus during pregnancy, suppression of uterine contractions until just prior to parturition and preparation of the breasts for lactation.

During the follicular phase of the menstrual cycle, low levels of progesterone are found in serum and saliva. During the luteal phase, the corpus luteum produces progesterone and levels increase sharply for a maximum of 5 to 10 days. If implantation of a fertilized ovum does not occur, a steep decline in these levels is seen at about 4 days prior to the menstrual period.

In postmenopausal women it has been shown that a combination of progesterone plus estrogen provides an optimal hormonal profile for prevention of cardiovascular disease, osteoporosis and endometrial protection. Progesterone has also been suggested to alleviate the symptoms of premenstrual syndrome.

Measurement of progesterone levels is useful in the detection of luteal insufficiency in the early stages of pregnancy. Measurement of progesterone levels is also useful to monitor women on progesterone replacement therapy for relief of symptoms or prevention of some of the long term problems associated with hormone deficiency, including osteoporosis and heart disease.

Interpretation of Results
Salivary levels of naturally produced hormones reflect the free fraction (non-protein bound fraction) of the hormone in the blood. Levels are about 1% of the total serum concentration (although individual variability is relatively broad). Salivary levels of those on oral replacement show the same pattern. Transdermal cream users show much higher saliva progesterone levels. (See results interpretation - Transdermal Hormone Delivery - for explanation). Trough levels are just prior to next scheduled dose and were used to determine our ranges. Ranges of progesterone in saliva for those with and without supplementation are outlined below. Progesterone is measured in ng/ml.

        Endogenous                                                Supplemented

Premenopausal                                          Oral Replacement*         0.1- 0.5
    follicular             < 0.1
    luteal             0.1 - 0.5                            Transdermal Cream*       1.0 –10
Postmenopausal     <0.05

*Ranges represent levels 8 - 12 hrs after last dose or application.

References
1) The Writing Group for the PEPI Trial: Effects of estrogen or estrogen/progestin regimens on heart disease risk factors in postmenopausal women. JAMA 1995;273:199-208
2) Finn MM, Gosling JP, Tallon DF, Baynes S et al.: The Frequency of Salivary Progesterone Sampling and the Diagnosis of Luteal Phase Insufficiency. Gynecol Endocrinol 1992;6:127-134
3) Ellison, P: Measurement of salivary progesterone. Ann N Y Acad Sci 1992:161-176
4) Lee, J: Natural progesterone. BLL Publishing, Sebastopol, CA 1993
5) Lipson, S & Ellison P: Development of protocols for the application of salivary steroid analysis to field conditions. American Journal of Human Biology 1989;1:249-255