Normal Progesterone Range for Postmenopausal Women on HRT
There is no established "normal range" for progesterone levels in postmenopausal women on HRT, and routine monitoring of progesterone levels is not recommended or clinically useful. 1
Why Progesterone Levels Are Not Monitored
Progesterone is prescribed based on dose adequacy for endometrial protection, not target serum levels. The goal is to prevent endometrial hyperplasia in women with an intact uterus taking estrogen, not to achieve specific blood concentrations. 1
Dosing is standardized based on clinical trials demonstrating endometrial safety, not individualized hormone measurements. 1, 2
Evidence-Based Progesterone Dosing in HRT
For Women with an Intact Uterus
Micronized progesterone 200 mg orally at bedtime is the preferred first-line progestin due to lower rates of venous thromboembolism and breast cancer risk compared to synthetic progestins like medroxyprogesterone acetate. 1, 3
Alternative dosing of micronized progesterone 100 mg daily for 25 days per month has been shown to efficiently protect the endometrium by fully inhibiting mitoses and inducing amenorrhea in over 90% of postmenopausal women. 2
Medroxyprogesterone acetate 10 mg daily for 12-14 days per cycle is an acceptable alternative, though less preferred. 1
Combined estradiol/progestin patches (e.g., 50 μg estradiol + 10 μg levonorgestrel daily) provide continuous progestin delivery without need for level monitoring. 1
Clinical Endpoints That Matter
Endometrial protection is assessed by absence of breakthrough bleeding, endometrial thickness on ultrasound (<5 mm), and periodic endometrial sampling if indicated—not by measuring progesterone levels. 2, 4
Studies demonstrate that 100 mg daily micronized progesterone produces 61% quiescent endometrium without mitosis, 23% mildly active with rare mitoses, and no cases of hyperplasia. 2
Amenorrhea rates of 91-93% at 6 months serve as a clinical marker of adequate progestin effect. 2, 4
Common Pitfalls to Avoid
Do not order serum progesterone levels to "monitor" HRT—this is not evidence-based and provides no clinically actionable information. 1
Do not adjust progesterone doses based on serum levels—adjust based on bleeding patterns, tolerability, and endometrial surveillance. 1, 2
Do not use higher doses than necessary—the lowest effective dose for endometrial protection minimizes side effects like headaches and vaginal bleeding, which occur in 6-21% of patients and lead to discontinuation. 5
What Actually Gets Monitored in HRT
Symptom control (vasomotor symptoms, sleep, mood) guides estrogen dosing. 1
Bleeding patterns guide progestin adequacy—persistent irregular bleeding warrants endometrial evaluation, not hormone level checks. 2, 4
Mammography per standard guidelines for breast cancer surveillance. 1
Clinical assessment for adverse effects including cardiovascular events, thromboembolism, and breast tenderness. 1, 6