Progesterone Interpretation by Decade of Life
At a glance
- What sets the reading / cycle phase, menopausal status, dose, route and hours since dose
- Prometrium 100 mg daily / mean Cmax 17.3 ng/mL; Tmax 1.5 hours in postmenopausal women [2]
- Prometrium 200 mg daily / mean Cmax 38.1 ng/mL; Tmax 2.3 hours [2]
- Spread between women / SD 21.9 ng/mL at 100 mg and 37.8 ng/mL at 200 mg [2]
- Approved use / endometrial protection with conjugated estrogens in postmenopausal women with a uterus [1]
- Other approved use / secondary amenorrhea; 400 mg at bedtime for 10 days [1]
- Bedtime dosing / label warns of transient dizziness and drowsiness [1][2]
- Compounded progesterone / not FDA-approved; FDA does not verify safety, effectiveness or quality [3]
Is there a normal level for each decade?
The Prometrium label does not give age-by-decade reference intervals. Its pharmacokinetic data are from postmenopausal women given daily oral doses, and its approved uses are endometrial protection in postmenopausal women taking conjugated estrogens tablets and secondary amenorrhea [1][2]. The label says the capsules should not be used during pregnancy and are not indicated in children [2]. Those data do not supply age-specific ranges for any other group, such as teenagers or pregnant women.What the label's numbers mean
After five daily 100 mg doses in postmenopausal women, mean Cmax was 17.3 ng/mL (SD 21.9) with Tmax 1.5 hours; after 200 mg daily, mean Cmax was 38.1 ng/mL (SD 37.8) with Tmax 2.3 hours [2]. Maximum concentrations were reached within 3 hours [2]. These are mean post-dose values, not a normal range for a 30-year-old or a 60-year-old. The standard deviations are roughly as large as or larger than the means, so one result can sit far from the mean at the same dose [2]. Food increased bioavailability compared with fasting after a 200 mg dose [2].How dose and schedule matter
For endometrial protection the label's regimen is 200 mg at bedtime for 12 days sequentially per 28-day cycle, with daily conjugated estrogens, in a postmenopausal woman with a uterus [1]. For secondary amenorrhea it is 400 mg at bedtime for 10 days [1]. The patient leaflet says to take it at bedtime because some women become very drowsy or dizzy; during initial therapy a few women had extreme dizziness, blurred vision, slurred speech, difficulty walking or loss of consciousness [1][2].The label's endometrial trial used fixed doses, not a serum target. By 36 months, hyperplasia occurred in 6% of women taking conjugated estrogens 0.625 mg plus cyclic Prometrium 200 mg, 64% taking estrogen alone and 3% taking placebo [1]. That is a trial result for a regimen, not a threshold for an individual blood level.
What else matters besides the number
The label's contraindications are separate from any lab value: peanut allergy (capsules contain peanut oil), abnormal genital bleeding of unknown cause, known, suspected or past breast cancer, active or past DVT or PE, active or past arterial thromboembolic disease, and known liver dysfunction or disease [1].Compounded progesterone is not FDA-approved, and FDA does not verify its safety, effectiveness or quality before marketing [3]. The label describes Prometrium capsules, not compounded products [2][3].
Frequently asked questions
Can I interpret my progesterone by age decade alone?
No. The label gives post-dose concentrations in postmenopausal women and dosing for two indications, not age-by-decade ranges [1][2]. A level is read with cycle phase, menopausal status, dose, route and hours since dose.
What levels does the label report after oral progesterone?
After five daily 100 mg doses, mean Cmax was 17.3 ng/mL (SD 21.9) at 1.5 hours; at 200 mg daily it was 38.1 ng/mL (SD 37.8) at 2.3 hours [2]. Maximum concentrations were reached within 3 hours [2].
Does food change an oral progesterone level?
The label says food increased progesterone bioavailability compared with fasting after a 200 mg dose in postmenopausal women [2].
Does the label give a serum target for endometrial protection?
No. The label's endometrial trial used fixed doses, not a serum target [1]. Hyperplasia by 36 months was 6% with conjugated estrogens plus cyclic Prometrium 200 mg, 64% with estrogen alone and 3% with placebo [1].
References
- U.S. National Library of Medicine, DailyMed. Prometrium progesterone capsules (Acertis), Rev. 02/2026 prescribing information. Prometrium progesterone capsules (Acertis), Rev. 02/2026 label
- U.S. Food and Drug Administration. U.S. Food and Drug Administration
- Compounding and the FDA: Questions and Answers | FDA. Compounding and the FDA: Questions and Answers | FDA