Progesterone Levels in Women on HRT
The statement that women on HRT can have progesterone levels up to 10 ng/ml is misleading and not clinically relevant—progesterone levels are not routinely monitored in HRT, and therapeutic dosing is based on endometrial protection rather than serum levels. 1, 2
Why Progesterone Levels Are Not Monitored in HRT
No routine monitoring of progesterone levels is required in women on HRT. 1, 2 The guidelines are clear:
- Annual clinical review should focus on compliance, bleeding patterns, and symptom control—not laboratory values. 1, 2
- Monitoring tests are only prompted by specific symptoms or concerns, not routine progesterone measurements. 1, 2
The therapeutic goal is endometrial protection and symptom management, not achieving specific serum progesterone concentrations.
Standard Progesterone Dosing for HRT
The appropriate progesterone regimen depends on whether you're using sequential or continuous therapy:
Sequential Regimens (for women wanting monthly bleeding):
- Micronized progesterone 200 mg orally daily for 12-14 days per 28-day cycle is the preferred first-line option. 2, 3
- Alternative: Medroxyprogesterone acetate 10 mg daily for 12-14 days per month. 2, 4
- Alternative: Dydrogesterone 10 mg daily for 12-14 days per month. 2
Continuous Regimens (for women wanting amenorrhea):
- Micronized progesterone 100 mg orally daily continuously. 2, 5
- Alternative: Medroxyprogesterone acetate 2.5 mg daily continuously. 2
- Alternative: Dydrogesterone 5 mg daily continuously. 2
What Serum Levels Actually Mean (When Measured)
While not routinely monitored, research shows:
- Micronized progesterone 200 mg orally produces adequate tissue levels for endometrial protection. 6, 3
- In frozen embryo transfer protocols (not standard HRT), serum progesterone below 9-11 ng/ml has been associated with worse outcomes, but this threshold does not apply to menopausal HRT. 7
- Serum levels vary significantly based on route of administration—vaginal progesterone produces lower serum levels than oral despite adequate endometrial protection. 7
Critical Pitfalls to Avoid
Never use progesterone for fewer than 12 days per cycle in sequential regimens—this provides inadequate endometrial protection and increases hyperplasia risk. 2
The 10 ng/ml threshold mentioned in your question appears to conflate pregnancy/fertility medicine with menopausal HRT—these are entirely different clinical contexts. 7 In standard HRT:
- Dosing is based on proven endometrial protection, not serum levels. 1, 2
- The focus is on histologic endpoints (preventing hyperplasia) rather than achieving specific progesterone concentrations. 5, 8
Preferred Formulation
Micronized progesterone is preferred over synthetic progestins due to lower cardiovascular and thrombotic risk. 2, 6, 3 This recommendation comes from multiple societies including the American Heart Association and American College of Cardiology. 2
Pair progesterone with transdermal 17β-estradiol 50-100 μg daily rather than oral estrogens for optimal cardiovascular safety. 2