When are hormone blood draws recommended for women and what do the tests typically measure?

Hormone Blood Draw Recommendations for Women

Hormone blood draws for women are recommended when there are symptoms of reproductive endocrine disorders, including menstrual irregularity, infertility, weight gain, hirsutism, and galactorrhoea, with specific tests timed according to the menstrual cycle phase to ensure accurate results. 1

When Hormone Testing is Recommended

Hormone testing is indicated in the following clinical scenarios:

1. Menstrual Irregularities

• Polymenorrhoea (cycles <23 days)
• Oligomenorrhoea (cycles >35 days)
• Amenorrhoea (no bleeding >6 months) 1
• Secondary amenorrhea (absence of menses for ≥90 days) 2

2. Signs of Reproductive Disorders

• Infertility (inability to conceive after 12+ months of regular unprotected intercourse)
• Hirsutism (male pattern hair growth)
• Obesity or significant weight gain, especially truncal obesity (WHR >0.9)
• Galactorrhoea (breast milk expression in non-lactating women) 1

3. Suspected Premature Ovarian Insufficiency (POI)

• Women under 40 years with menstrual disturbances and elevated gonadotropins
• Female cancer survivors treated with gonadotoxic chemotherapy or radiotherapy 1

Common Hormone Tests and Timing

Gonadotropins (LH and FSH)

• When to test: Days 3-6 of menstrual cycle
• Method: Average of three measurements taken 20 minutes apart
• Abnormal findings:
  • LH/FSH ratio >2 (suggestive of PCOS)
  • FSH >35 IU/l (suggestive of ovarian insufficiency)
  • LH >11 IU/l 1

Estradiol

• When to test: Early follicular phase (days 3-6)
• Significance: Low levels may indicate ovarian insufficiency; helps interpret FSH results 1

Progesterone

• When to test: Mid-luteal phase (typically 7 days before expected menses)
• Abnormal findings: <6 nmol/l indicates anovulation
• Common causes: PCOS, hypophyseal adenoma, hyperprolactinaemia 1

Testosterone

• When to test: Days 3-6 of cycle
• Abnormal findings: >2.5 nmol/l
• Common causes: PCOS, valproate therapy, non-classical adrenal hyperplasia
• Note: Most frequently abnormal biochemical marker in PCOS (70% sensitivity) 1, 3

Prolactin

• When to test: Morning resting levels (not post-seizure)
• Abnormal findings: >20 μg/l
• Note: May be mildly elevated in epilepsy patients; rule out hypothyroidism or pituitary tumors 1

Additional Tests for Specific Conditions

• Androstenedione: >10.0 nmol/l may indicate adrenal/ovarian tumor
• DHEAS: Age-specific elevated levels may indicate non-classical congenital adrenal hyperplasia
• Glucose/insulin: Fasting levels to assess insulin resistance (common in PCOS) 1

Special Considerations for Timing

1. For regular cycles: Test on specific days as noted above
2. For amenorrhea: Random FSH and estradiol measurements
3. For oligomenorrhea: Test during early follicular phase (days 2-5) 1
4. If on hormonal contraception: Ideally test after discontinuing for at least two months 1

Common Pitfalls in Hormone Testing

1. Improper timing: Hormone levels fluctuate throughout the menstrual cycle; testing at incorrect times can lead to misinterpretation
2. Single measurements: Especially for LH/FSH, single measurements may be misleading due to pulsatile release patterns
3. Post-seizure testing: Prolactin levels can be falsely elevated after seizures 1
4. Assay variability: Different laboratories may use different reference ranges; values should be interpreted according to the specific laboratory's normal ranges 1
5. Relying solely on LH/FSH ratio: This has low sensitivity (41-44%) for diagnosing PCOS and should not be used as the sole diagnostic criterion 3

Imaging in Conjunction with Hormone Testing

• Pelvic ultrasound: Indicated when clinical features or hormone tests suggest ovarian pathology
• Transvaginal ultrasound: More sensitive than transabdominal for detecting structural abnormalities
• Timing: Days 3-9 of cycle for optimal visualization of follicles 1
• Findings in PCOS: >10 peripheral cysts (2-8 mm diameter) with thickened ovarian stroma 1

By following these recommendations for hormone testing in women, clinicians can more accurately diagnose and manage reproductive endocrine disorders, improving outcomes related to fertility, quality of life, and long-term health.