Blood Test for Menopause: FSH and Estrogen Levels
Blood tests for menopause primarily involve measuring follicle-stimulating hormone (FSH) and estradiol (estrogen) levels, though these tests alone are not definitive for determining menopausal status and should be interpreted alongside clinical symptoms and menstrual history. 1
Key Components of Menopause Blood Testing
- FSH and estradiol are the primary hormone levels that should be checked when assessing menopausal status 1
- For women under age 60 with amenorrhea for ≥12 months (in the absence of medications like chemotherapy, tamoxifen, or ovarian suppression), both FSH and estradiol should be in the postmenopausal range to confirm menopause 2, 1
- Luteinizing hormone (LH) may be checked as clinically indicated to provide additional information about ovarian function 1
- Prolactin should be measured when clinically indicated to rule out other causes of menstrual irregularity 1
Interpretation of FSH and Estradiol Results
- Postmenopausal FSH levels are typically 10-15 times higher than premenopausal levels 3
- Estradiol levels are typically low in postmenopausal women 3
- However, significant overlap exists in hormone values between premenopausal, perimenopausal, and postmenopausal women 4, 5
- No single FSH value can reliably distinguish between premenopausal, perimenopausal, and postmenopausal status 5
- The commonly used FSH cutoff of >35-40 mIU/mL for postmenopausal status is not reliable when used alone 5, 6
Clinical Scenarios Requiring Testing
- When women present with irregular menstrual cycles 1
- When women present with vasomotor symptoms (hot flashes, night sweats) 1
- Before initiating hormone therapy 1
- After chemotherapy to assess ovarian function 1
- For women taking tamoxifen or toremifene who are under age 60 2, 1
- For women who have undergone hysterectomy but still have their ovaries 1
Limitations and Considerations
- FSH levels can fluctuate significantly during perimenopause, with levels sometimes rising to the postmenopausal range before returning to premenopausal levels 4, 3
- A single elevated FSH measurement is insufficient to confirm menopause; at least two consecutive high FSH evaluations are recommended 6
- Amenorrhea after chemotherapy is not a reliable indicator of menopause, as ovarian function may still be intact or resume despite absence of menses 2, 1
- It is not possible to accurately determine menopausal status in women receiving LHRH agonists or antagonists 2, 1
- Serum FSH and/or estradiol levels alone are not accurate enough to definitively diagnose perimenopause 7
Best Practice Recommendations
- Diagnose menopause based primarily on clinical symptoms and menstrual history, with hormone testing as supportive evidence 7
- For perimenopausal women who become amenorrheic and later develop bleeding, serial estradiol levels can help determine if ovarian function has returned 1
- For women over 50 years of age with menopausal symptoms, FSH testing may be more reliable 6
- Consider Anti-Müllerian hormone (AMH) testing to provide additional information on ovarian reserve status, though normative data in perimenopausal women are limited 1