Confirming Menopause as the Cause of Amenorrhea
To confirm if amenorrhea is due to menopause, measure FSH and estradiol levels, with high FSH and low estradiol in the postmenopausal range being diagnostic when combined with 12 or more months of amenorrhea in women under 60 years of age. 1
Diagnostic Criteria for Menopause
Menopause is defined as the permanent cessation of menses resulting from ovarian follicular depletion. The following criteria can be used to confirm menopause:
- Prior bilateral oophorectomy (surgical menopause) 2
- Age ≥60 years (presumptive diagnosis) 2
- Age <60 years with amenorrhea for 12 or more consecutive months, plus FSH and estradiol in the postmenopausal range 2, 1
- For women taking tamoxifen or toremifene and age <60 years, FSH and plasma estradiol levels in the postmenopausal range 2
Laboratory Testing Algorithm
- Rule out pregnancy first with a pregnancy test 3
- Measure FSH and estradiol levels 1
- High FSH (typically >30-40 mIU/mL) and low estradiol (<20 pg/mL) suggest menopause 4
- Additional hormonal testing if results are equivocal:
Special Considerations
Women Taking Hormone Medications
- If taking tamoxifen or toremifene, rely on FSH and estradiol levels rather than amenorrhea alone 2
- It is not possible to assign menopausal status to women receiving LHRH agonists or antagonists 2
Post-Chemotherapy Amenorrhea
- Amenorrhea following chemotherapy is not a reliable indicator of menopause 2
- Ovarian function may still be intact or resume despite amenorrhea 2
- Serial measurements of FSH and estradiol are needed to confirm menopausal status 2
Age Considerations
- Average age of menopause onset in the United States is 51 years 6
- Women under 40 years with amenorrhea and elevated FSH should be evaluated for primary ovarian insufficiency rather than natural menopause 3
Common Pitfalls to Avoid
- Relying solely on amenorrhea duration: While 12 months of amenorrhea strongly supports menopause diagnosis, hormonal confirmation is necessary, especially in younger women 1
- Single hormone measurement: A single FSH measurement may be misleading; consider serial measurements if results are borderline 4
- Ignoring medication effects: Certain medications can affect hormone levels and menstrual patterns 2
- Overlooking other causes: Secondary amenorrhea can also be caused by polycystic ovary syndrome, hypothalamic amenorrhea, or hyperprolactinemia 3
By following these diagnostic criteria and testing algorithms, clinicians can accurately determine whether amenorrhea is due to menopause or another condition, allowing for appropriate management decisions that will impact the patient's long-term health outcomes.