What labs should be ordered for female hormone replacement therapy?

Laboratory Tests for Female Hormone Replacement Therapy

For female hormone replacement therapy, the essential laboratory tests should include follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol, and thyroid function tests. These tests form the cornerstone of hormonal assessment before initiating and monitoring hormone replacement therapy (HRT).

Initial Laboratory Evaluation

Essential Baseline Tests:

• FSH and LH: To confirm menopausal status and assess pituitary function 1
• Estradiol: To determine baseline estrogen levels 1
• Thyroid function tests: TSH and free T4 to rule out thyroid dysfunction that may mimic menopausal symptoms 1
• Complete blood count: To assess overall health status
• Comprehensive metabolic panel: Including liver and renal function tests 1
• Lipid profile: To assess cardiovascular risk factors 2

Additional Tests Based on Clinical Context:

• Anti-Müllerian hormone (AMH): For assessment of ovarian reserve, particularly in younger women with suspected premature ovarian insufficiency 1
• Testosterone: For women with symptoms of androgen deficiency (low libido, fatigue) 1
• Sex hormone binding globulin (SHBG): To assess bioavailable hormone levels, especially important with oral estrogen preparations 2, 3

Timing of Laboratory Testing

For accurate assessment of hormone levels:

• Tests should be performed during the early follicular phase (days 2-5) of the menstrual cycle in women who are still menstruating 1
• For women with amenorrhea, testing can be done at any time
• For women currently on HRT, tests should be conducted after a washout period of at least 2 weeks if possible, or at trough levels (before next dose) 2, 3

Monitoring Tests During HRT

Follow-up Testing Schedule:

• 3-6 months after initiation: FSH, estradiol, and any parameters that were abnormal at baseline 2
• Annually thereafter: Complete metabolic panel, lipid profile, and hormone levels as needed 2

Special Considerations:

• Women on oral estrogen preparations require closer monitoring of liver function and SHBG levels 2, 3
• Women with intact uterus on combined estrogen-progestin therapy should have endometrial assessment if abnormal bleeding occurs 1, 2
• Women with history of breast cancer may need more frequent monitoring of hormone levels 1

Interpretation of Results

• FSH > 40 IU/L with estradiol < 20 pg/mL typically confirms menopause in women over 45 years 1, 2
• In women on HRT, estradiol levels should be maintained between 50-100 pg/mL for symptom control 2, 3
• FSH levels will be suppressed in women on adequate estrogen therapy 3
• Higher BMI is associated with higher endogenous estradiol levels in non-users of HRT, which may affect dosing requirements 3

Common Pitfalls to Avoid

• Do not rely solely on FSH levels to diagnose menopause in women taking hormonal contraceptives or those who recently discontinued them
• Avoid testing hormone levels during the luteal phase of the menstrual cycle
• Remember that transdermal and vaginal estrogen preparations have less impact on SHBG and other laboratory parameters than oral preparations 1, 2
• Be aware that hormone levels in transgender and gender-diverse individuals may need to be interpreted differently based on their affirmed gender and duration of hormone therapy 1

By following this structured approach to laboratory testing for female hormone replacement therapy, clinicians can appropriately assess hormonal status, monitor treatment efficacy, and minimize potential adverse effects of therapy.