Hormonal Testing for Female Reproductive Dysfunction

Core Hormone Panel and Timing

• The American College of Neurology recommends measuring FSH and LH between cycle days 3-6, with the most accurate assessment calculated as the average of three blood draws taken 20 minutes apart, to capture baseline gonadotropin levels before follicular recruitment begins 1, 2
• An LH/FSH ratio >2 suggests polycystic ovary syndrome (PCOS) and likely anovulation, while FSH >35 IU/L and LH >11 IU/L indicate ovarian failure, and LH <7 IU/mL may indicate hypothalamic dysfunction 1, 2
• Progesterone measurement during mid-luteal phase is the most reliable hormonal indicator of ovulation, with progesterone <6 nmol/L indicating anovulation 1, 2

Additional Hormones to Measure

• Estradiol should be measured on days 3-6 alongside FSH/LH, as it is essential for assessing ovarian function 3, 4, 5
• TSH is essential as thyroid dysfunction commonly causes menstrual irregularity and must be excluded 1
• Prolactin should be measured in morning resting samples, with levels >20 μg/L being abnormal 1

Clinical Context Matters

• The hormone panel is indicated for women presenting with menstrual irregularity, infertility, galactorrhea, or failure to initiate or progress through puberty 1, 3
• PCOS typically shows LH/FSH ratio >2, elevated LH throughout the cycle, and normal to high estradiol, while functional hypothalamic amenorrhea (FHA) shows low gonadotropins, LH/FSH ratio <1, and low estradiol with thin endometrium 1, 6

Critical Pitfalls to Avoid

• Measurements taken at the wrong cycle phase render results uninterpretable, and hormonal contraceptives suppress normal FSH and LH patterns and should be discontinued at least 2 months before testing 1, 2
• Antiepileptic drugs can impact hormone levels and cause reproductive endocrine disorders 1

For Irregular or Absent Cycles

• Women with irregular cycles may benefit from anti-Müllerian hormone (AMH) testing, which does not vary by menstrual day and is not affected by exogenous estrogen or progesterone, but interpretation requires caution in women under age 25 due to significant fluctuations 2, 3, 4

When to Refer

• Endocrinology and/or gynecology consultation is warranted for prepubertal females with no signs of puberty by age 13 years, primary amenorrhea by age 16 years, postpubertal females with menstrual cycle dysfunction suggestive of premature ovarian insufficiency, or any patient diagnosed with ovarian insufficiency requiring sex steroid replacement therapy consideration 3, 5