What is the best time to check hormone levels for hormone replacement therapy (HRT)?

Optimal Timing for Hormone Level Testing in HRT

For testosterone replacement therapy, measure morning total and free testosterone levels between 8 AM and 10 AM before initiating treatment, then recheck at 2-3 months after starting therapy or any dose adjustment. 1, 2

Pre-Treatment Baseline Assessment

Initial Testing Protocol

• Draw morning testosterone levels between 8 AM and 10 AM to capture peak physiologic levels and ensure accurate baseline measurement 1
• Measure both total testosterone AND free testosterone by equilibrium dialysis, particularly in patients with obesity where sex hormone-binding globulin may be low 1
• Repeat abnormal testosterone levels on a separate occasion before initiating treatment—at least 2 separate assessments of frankly low morning free testosterone are required 1
• Include luteinizing hormone (LH) and follicle-stimulating hormone (FSH) if testosterone is low to distinguish primary from secondary hypogonadism 1

Additional Baseline Parameters

• PSA and digital rectal examination 1
• Hematocrit or hemoglobin level 1
• Assessment of voiding symptoms and sleep apnea history 1

Post-Treatment Monitoring Timeline

Initial Follow-Up

• First follow-up visit at 1-2 months after initiating therapy to assess efficacy and consider dose escalation if clinical response is inadequate with suboptimal levels 1, 2
• Formal testosterone level testing at 2-3 months after treatment initiation or after any dose change 1, 2

Ongoing Monitoring Schedule

• Every 3-6 months for the first year, then yearly thereafter once stable levels are confirmed 1, 2
• At each visit, measure serum testosterone, PSA, and hematocrit/hemoglobin 1

Timing Based on Formulation Type

Injectable Testosterone (Cypionate/Enanthate)

• Measure levels midway between injections (typically day 5-7 for weekly injections, or day 7-10 for biweekly injections) 1, 2
• Peak levels occur 2-5 days post-injection, with return to baseline by 10-14 days 1, 2
• Target mid-normal values (500-600 ng/dL) when measuring at the midpoint 1

Transdermal Preparations (Gels/Patches)

• Can measure at any time for gels, though concentrations vary substantially in an unpredictable way 1
• For patches, peak values occur 6-8 hours after application 1
• The day-to-day stability of transdermal preparations makes timing less critical than with injections 1

Critical Pitfalls to Avoid

Common Errors

• Do not test testosterone levels at random times of day—circadian variation makes afternoon or evening levels unreliable for diagnosis 1
• Do not rely on total testosterone alone in patients with obesity—low sex hormone-binding globulin can falsely lower total testosterone while free testosterone remains normal 1
• Do not test too early after starting treatment—allow 2-3 months for steady-state levels to be achieved 1, 2
• Do not ignore the injection timing—testing immediately after or just before the next injection will give misleading results for injectable formulations 1

Dose Adjustment Considerations

• If clinical response is suboptimal AND testosterone levels are low-normal or below, increase the dose 1
• If hematocrit rises above reference range, temporarily withhold therapy, reduce dosage, or perform phlebotomy 1, 2
• Target mid-to-upper normal range for optimal treatment response 1, 2