Medroxyprogesterone Acetate Dosing for Endometrial Protection in PCOS
For women with PCOS who are not attempting to conceive, medroxyprogesterone acetate (Provera) should be administered at 10 mg daily for 12-14 days per month to provide endometrial protection and prevent endometrial hyperplasia. 1, 2
Primary Dosing Regimen
- The standard dose is 10 mg medroxyprogesterone acetate daily for 12-14 days per month in a sequential (cyclic) regimen 1, 2
- This dosing provides adequate endometrial protection while suppressing circulating androgen levels and pituitary gonadotropin levels in women with PCOS 3
- The 12-14 day duration is critical—shorter durations provide inadequate endometrial protection 1
Alternative Continuous Regimen
- For women who prefer amenorrhea, 2.5 mg medroxyprogesterone acetate daily continuously can be used instead of the cyclic regimen 1, 2
- This continuous approach avoids withdrawal bleeding but still provides endometrial protection 1
Clinical Context and Rationale
The primary goal of progestin therapy in PCOS patients not attempting conception is endometrial cancer risk reduction, as chronic anovulation leads to unopposed estrogen exposure 3. Key benefits include:
- Suppression of ovarian androgen secretion 3
- Reduction in LH levels (approximately 48% decrease from baseline) 4
- Decrease in total testosterone levels (approximately 40% reduction) 5, 6
- Improvement in free androgen index 5
- Reduction in acne and seborrhea scores 5
Important Metabolic Considerations
Medroxyprogesterone acetate does NOT adversely affect lipid or carbohydrate metabolism in PCOS patients when used at these doses:
- No significant changes in total cholesterol, HDL, LDL, or triglycerides over 6 months of treatment 5
- No adverse effects on insulin resistance or HOMA index over 3 months 7
- Total cholesterol to HDL ratio remains stable 5
This is particularly important since PCOS patients already have increased cardiovascular risk factors 3.
Preferred Alternative: Micronized Progesterone
While medroxyprogesterone acetate is effective, micronized progesterone 200 mg daily for 12-14 days per month is actually the preferred first-line option due to superior cardiovascular and metabolic safety profile 1. However, if medroxyprogesterone acetate is specifically chosen:
- It has extensive safety data and proven efficacy 1
- It is considered a third-line progestin option after micronized progesterone and dydrogesterone 1
- It provides reliable endometrial protection with good menstrual cycle control 5
Critical Pitfalls to Avoid
- Never use progestin for fewer than 12 days per cycle—this provides inadequate endometrial protection 1
- Do not use progestin alone without screening for diabetes and dyslipidemia first, as all PCOS patients require baseline metabolic assessment 3
- Avoid assuming oral contraceptive pills and cyclic progestins are equivalent—OCPs provide contraception and different metabolic effects, while cyclic MPA is specifically for endometrial protection in women not needing contraception 3
Monitoring Requirements
- Annual clinical review focusing on bleeding patterns and symptom control 1
- No routine laboratory monitoring required unless specific symptoms arise 1
- Fasting lipid profile and glucose tolerance testing should be performed at baseline before initiating therapy 3
When to Consider Combination Oral Contraceptives Instead
If the patient also needs contraception, combination oral contraceptive pills are preferred over cyclic progestins alone 3. OCPs provide:
- Suppression of ovarian androgen secretion 3
- Increased sex hormone binding globulin 3
- Reduced endometrial cancer risk 3
- Reliable contraception 3
However, the optimal progestin type and duration for endometrial cancer prevention specifically in PCOS remains incompletely defined 3.