The impact of micronized progesterone on the endometrium: a systematic review.
Level 1 - systematic review of randomized trials
Systematic literature review informing clinical recommendations on endometrial protection.
PubMed 27277331 · doi:10.1080/13697137.2016.1187123
What was done
A systematic literature review evaluated the evidence on micronized progesterone for endometrial protection in postmenopausal women with an intact uterus receiving estrogen therapy. An international expert panel synthesized the findings to formulate clinical recommendations regarding administration routes (oral, vaginal, transdermal), dosing schedules, and duration of use. The abstract does not report search databases, inclusion criteria, or study counts.
What was found
The abstract reports panel recommendations rather than pooled numerical data or effect sizes: 1. Oral micronized progesterone provides endometrial protection when used sequentially at 200 mg/day for 12-14 days per month for up to 5 years. 2. Vaginal micronized progesterone may provide endometrial protection when used sequentially for at least 10 days per month at 4% (45 mg/day) or every other day at 100 mg/day for up to 3-5 years (off-label use). 3. Transdermal micronized progesterone does not provide endometrial protection.
Why it matters
It clarifies effective regimens and routes for bioidentical progesterone in menopausal hormone therapy, explicitly advising that transdermal progesterone is ineffective for endometrial protection.
Limits
The abstract reports no numerical data, event rates, sample sizes, or number and designs of reviewed studies. Evidence for safety does not extend beyond 3 to 5 years, and vaginal administration remains an off-label use.
Cited by
- supports At least 100 to 200 mg of oral progesterone is required to adequately oppose estrogen at the endometrial level during hormone replacement therapy.