Laboratory Testing for Perimenopause
In perimenopausal women presenting with irregular cycles, vasomotor symptoms, mood changes, or sleep disturbance, routine hormonal testing is generally not necessary or recommended for diagnosis, as perimenopause is a clinical diagnosis based on age and symptoms. 1, 2
When Laboratory Testing Is NOT Indicated
Do not order FSH, LH, or estradiol levels in women aged 40-55 years with typical perimenopausal symptoms (irregular cycles, hot flashes, night sweats, mood changes, sleep disturbance) and no concerning features, as hormone levels fluctuate wildly during perimenopause and a single measurement is unreliable for diagnosis. 1, 2
Perimenopause is diagnosed clinically based on age (typically late 30s to early 50s), menstrual pattern changes, and characteristic vasomotor symptoms—not by laboratory values. 3, 4, 5
Essential Laboratory Tests to Order
The following tests should be ordered to exclude other treatable causes of symptoms that mimic perimenopause:
Mandatory First-Line Tests
Pregnancy test (urine or serum β-hCG) – Must be performed first in any woman with irregular cycles or amenorrhea to exclude pregnancy, as this is the most critical diagnosis not to miss. 1, 2
Thyroid-stimulating hormone (TSH) – Essential to identify hypothyroidism or hyperthyroidism, which causes identical symptoms (irregular cycles, mood changes, sleep disturbance, fatigue) and is a reversible cause requiring different treatment. 1, 2, 6
Complete blood count (CBC) – Indicated if heavy or irregular bleeding is present to assess for anemia from menorrhagia, which affects 25% of perimenopausal women. 7
Additional Tests Based on Clinical Presentation
Prolactin (morning resting sample) – Order if galactorrhea is present, cycles are absent >3 months, or if TSH is normal but symptoms persist; hyperprolactinemia (>20 μg/L) causes both menstrual irregularity and mood/sleep symptoms. 1, 2
FSH and LH (drawn days 3-6 of cycle, or anytime if amenorrheic) – Only order if premature ovarian insufficiency is suspected (age <40 years with amenorrhea >3 months); FSH >40 mIU/mL on two occasions 4 weeks apart confirms the diagnosis. 1, 2
Mid-luteal progesterone (drawn 7 days before expected menses) – Order if fertility is a concern or if distinguishing anovulation from ovulatory cycles will change management; levels <6 nmol/L indicate anovulation. 1, 2
Tests to Order If Hyperandrogenic Features Present
If the patient has hirsutism, acne, or significant weight gain, add:
Total testosterone (drawn days 3-6) – Levels >2.5 nmol/L suggest PCOS, which can present with irregular cycles in the perimenopausal age range. 1, 2
Fasting glucose and insulin – Order if BMI >25 kg/m² or clinical features of PCOS; glucose >7.8 mmol/L or glucose/insulin ratio >4 indicates insulin resistance requiring different management. 1, 2
Critical Pitfalls to Avoid
Do not use FSH levels to "diagnose" perimenopause in women aged 40-55 with typical symptoms—FSH fluctuates dramatically week-to-week during perimenopause, and a single elevated value does not confirm menopause nor does a normal value exclude perimenopause. 1, 2
Do not draw hormone levels while the patient is taking hormonal contraceptives or hormone therapy, as these medications suppress endogenous hormone production and render results uninterpretable. 2, 6
Do not measure prolactin immediately after stress, breast examination, or sexual activity, as these cause transient elevation; obtain a morning resting sample only. 8, 2
Do not assume amenorrhea equals menopause in women <45 years—always measure FSH twice (4 weeks apart) to confirm premature ovarian insufficiency, and obtain karyotype if confirmed to detect Turner syndrome. 2, 6
When to Refer for Specialist Evaluation
- Amenorrhea >3 months in women <40 years (premature ovarian insufficiency). 2, 6
- Prolactin >100 μg/L or any prolactin elevation with headaches or visual changes (pituitary adenoma). 8, 2
- Testosterone >5 nmol/L or rapid virilization (ovarian or adrenal tumor). 8, 2
- Persistent symptoms despite appropriate management or diagnostic uncertainty. 1, 6