Bloodwork for Perimenopause Evaluation
For routine perimenopause evaluation, order FSH and estradiol levels as the primary hormonal assessment, with LH and prolactin added only when clinically indicated by specific symptoms or to rule out other causes of menstrual irregularity. 1, 2
Primary Hormone Tests
FSH and estradiol are the cornerstone tests for assessing menopausal status in perimenopausal women, though they must be interpreted alongside clinical symptoms and menstrual history rather than in isolation. 2
- FSH levels should be measured, recognizing that perimenopause is characterized by wide fluctuations rather than steady increases. 2, 3
- Estradiol levels provide complementary information about ovarian function, though they also fluctuate significantly during the perimenopausal transition. 2, 3
- These hormone levels show substantial individual variation, with patterns ranging from premenopausal ovulatory cycles to transient postmenopausal-range values, even within the same woman over time. 4
Additional Hormones (Selective Use)
LH and prolactin should be reserved for specific clinical scenarios rather than routine screening:
- LH may be checked when additional information about ovarian function is needed or when FSH/estradiol results are ambiguous. 1, 2
- Prolactin should be measured to exclude hyperprolactinemia as an alternative cause of menstrual irregularity, particularly in women with amenorrhea or oligomenorrhea. 1, 2
- Anti-Müllerian hormone (AMH) may provide supplementary information about ovarian reserve, though normative data for perimenopausal women remain limited and it should not be used as a standalone test. 1, 2
Critical Interpretation Caveats
FSH is unreliable in several important clinical contexts:
- Women with prior chemotherapy or pelvic radiation exposure cannot have menopausal status reliably determined by FSH alone. 1, 2
- Women taking tamoxifen or toremifene require both FSH and estradiol in the postmenopausal range to confirm menopause, as these medications interfere with hormonal interpretation. 2
- Women receiving LHRH agonists or antagonists cannot have menopausal status accurately determined through hormone testing. 2
- Amenorrhea after chemotherapy does not reliably indicate menopause, as ovarian function may remain intact or resume despite absent menses. 2
Clinical Context for Testing
Order hormone testing when women present with:
- Irregular menstrual cycles or changes in bleeding patterns. 2, 5
- Vasomotor symptoms (hot flashes, night sweats). 2, 5
- Before initiating hormone therapy to establish baseline status. 2
- After chemotherapy to assess ovarian function recovery. 2
- Recurrent bleeding after amenorrhea (serial estradiol levels help determine if ovarian function has returned). 2
Additional Screening Beyond Hormones
Assess for medical conditions that can mimic or complicate perimenopause:
- Thyroid function tests (TSH, free T4) should be ordered, as thyroid disease commonly presents with symptoms overlapping perimenopause and significantly impacts quality of life. 1
- Glucose/diabetes screening should be performed, as metabolic changes during perimenopause increase risk. 1
Special Population: Post-Hysterectomy
For women who have undergone hysterectomy but retain their ovaries, FSH and estradiol levels remain the appropriate tests to determine menopausal status, since menstrual history cannot be used as a clinical marker. 1, 2
Key Clinical Pitfall
Do not rely on a single hormone measurement to diagnose perimenopause. The hallmark of perimenopause is hormonal fluctuation, with studies demonstrating that the same woman can show premenopausal, perimenopausal, and postmenopausal-range values at different time points. 3, 4 Ovulatory cycles can occur even within 16 weeks of the final menstrual period, and postmenopausal biochemical parameters do not guarantee permanent postmenopausal status. 4