Normal Progesterone Range in Postmenopausal Females
The normal progesterone range in postmenopausal women is very low, typically less than 0.20 ng/mL (or <0.64 nmol/L), reflecting the cessation of ovarian function.
Physiological Background
Progesterone levels in postmenopausal women are significantly lower than in premenopausal women due to:
- Cessation of ovulation and corpus luteum formation
- Lack of cyclic ovarian hormone production
- Minimal peripheral conversion of precursors to progesterone
Reference Values
Postmenopausal women have minimal progesterone production, with levels typically:
- Below detection limits of many standard assays
- Significantly lower than the luteal phase levels of 5-20 ng/mL seen in premenopausal women
Clinical Implications
Low progesterone levels in postmenopausal women are:
- Normal physiological state
- Not associated with specific pathology
- Expected finding in women who have been amenorrheic for ≥12 months
Exogenous Progesterone Considerations
When postmenopausal women receive hormone therapy that includes progesterone:
- Oral micronized progesterone at 100 mg daily produces mean plasma levels of approximately 4.6 ng/mL 1
- Oral micronized progesterone at 200 mg daily produces mean plasma levels of approximately 6.8 ng/mL 1
- Vaginal progesterone administration (100 mg) can achieve plasma levels of 10-15 ng/mL 2
Hormone Therapy Considerations
For postmenopausal women requiring hormone therapy:
- Women with intact uteri receiving estrogen therapy require progesterone/progestin to prevent endometrial hyperplasia 3
- Micronized progesterone (200 mg daily for 12-14 days every 28 days in sequential regimen) is recommended for endometrial protection 3
- Natural micronized progesterone has a more favorable safety profile than synthetic progestins 4
Measurement Considerations
When interpreting progesterone levels in postmenopausal women:
- Most standard laboratory assays have detection limits around 0.1-0.3 ng/mL
- Values below detection limit should be reported as "less than" the lower limit of detection
- Elevated progesterone levels in postmenopausal women not on hormone therapy warrant investigation
Potential Pitfalls
Important considerations when evaluating progesterone levels:
- Laboratory assay sensitivity varies between institutions
- Cross-reactivity with other steroid hormones may affect results
- Recent hormone therapy administration can significantly affect measured values
- Adrenal production accounts for minimal progesterone in postmenopausal women
Remember that while progesterone levels are very low in postmenopausal women, this represents a normal physiological state rather than a deficiency requiring treatment in the absence of specific indications for hormone therapy.