Which is more reliable for menopause evaluation, FSH (Follicle-Stimulating Hormone) or LH (Luteinizing Hormone)?

FSH is More Reliable Than LH for Menopause Evaluation

FSH is the preferred hormone for menopause evaluation, as it is the hallmark of menopausal transition, though it should not be used alone for diagnosis without considering clinical symptoms and menstrual history. 1

Diagnostic Approach to Menopause

Primary Diagnostic Criteria

• Menopause is clinically defined as 12 consecutive months without menstruation
• Natural menopause occurs at a median age of 51 years in the United States (normal range 40-60 years)
• The most reliable approach combines:
  1. Age assessment
  2. Menstrual pattern evaluation
  3. Symptom assessment
  4. Laboratory testing as supportive evidence only

Laboratory Testing Guidelines

• FSH levels >40 IU/L suggest menopause, but a single elevated value is not diagnostic 1
• For women still menstruating, FSH should be measured during early follicular phase (days 2-5)
• For women with amenorrhea of 12+ months, timing of FSH measurement is not critical
• Two elevated serum FSH levels in the menopausal range are needed for diagnosis of premature ovarian insufficiency 1

Why FSH is Preferred Over LH

FSH is the primary hormone used for menopause evaluation because:

1. The monotropic rise in FSH is the hallmark of the menopausal transition 2
2. FSH levels typically rise earlier and more consistently than LH during perimenopause
3. Clinical guidelines specifically mention FSH (not LH) as the laboratory marker for assessing menopause 1

Limitations of Hormone Testing

Despite FSH being preferred, important limitations exist:

• FSH levels can fluctuate significantly during perimenopause, with levels sometimes returning to premenopausal range 3, 4
• A single FSH measurement is unreliable for determining menopausal status 5
• Studies show that 40.6% of women with one high FSH measurement had normal levels in subsequent testing 6
• Ovulatory cycles can still occur even after FSH reaches postmenopausal range 1

Best Practice Recommendations

For accurate menopause evaluation:

1. Base diagnosis primarily on clinical criteria (12 months of amenorrhea)
2. Use FSH testing as supportive evidence, not as the sole diagnostic criterion
3. When testing FSH:
   • Obtain at least two measurements showing elevated levels (>40 IU/L)
   • For women still having periods, test during early follicular phase (days 2-5)
   • For women using hormonal contraception, be aware that FSH can still be measured but interpretation requires caution 7

Common Pitfalls to Avoid

• Relying solely on laboratory values without clinical correlation
• Using a single FSH measurement to confirm menopause
• Failing to consider other causes of amenorrhea (thyroid disease, hyperprolactinemia)
• Not accounting for the effects of hormonal medications on FSH levels
• Assuming fertility has ended based on elevated FSH (women can still ovulate during perimenopause)

FSH remains the most useful hormonal marker for menopause evaluation, but should always be interpreted in the context of clinical symptoms and menstrual history.