What labs should be rechecked 8 weeks after starting testosterone (testosterone) for hypogonadism?

Laboratory Monitoring at 8 Weeks After Starting Testosterone for Hypogonadism

At 8 weeks after initiating testosterone therapy, you should measure serum testosterone levels to confirm achievement of normal concentrations, along with hematocrit and PSA to monitor for adverse effects. 1

Core Laboratory Tests at 8 Weeks

Testosterone Level

• Measure serum testosterone at 2-3 months (8-12 weeks) after treatment initiation to verify that normal testosterone concentrations are being achieved 1
• The timing of measurement depends on the formulation used:
  • For testosterone injections: Measure midway between injections, targeting a mid-normal value of 500-600 ng/dL 1
  • For transdermal preparations (gels/patches): Can be measured at any time, though peak values occur 6-8 hours after application 1
• This 8-week timepoint aligns with evidence showing improvements in sexual function and other outcomes at this interval 1

Hematocrit

• Monitor hematocrit at regular intervals during testosterone therapy to detect polycythemia, a known adverse effect 2
• Elevated hematocrit is a safety concern that requires monitoring throughout treatment 2

Prostate-Specific Antigen (PSA)

• Check PSA levels at set intervals as part of strict follow-up protocols for testosterone therapy 2
• PSA monitoring is essential for prostatic safety surveillance 3

Additional Monitoring Considerations

After Initial 8-Week Assessment

• Once stable testosterone levels are confirmed on a given dose, monitoring every 6-12 months is typically sufficient 1
• Any dose adjustments require repeat testosterone measurement 2-3 months after the change 1

Clinical Correlation

• Laboratory values must be correlated with clinical symptoms and treatment response 4
• Assess for improvement in hypogonadal symptoms including libido, sexual function, energy, and body composition 3, 5

Common Pitfalls to Avoid

• Failing to adjust timing of testosterone measurement based on formulation type: Injectable testosterone requires midpoint measurement between doses, while transdermal preparations have different kinetics 1
• Not monitoring hematocrit and PSA: These safety parameters are critical for detecting adverse effects that may require dose adjustment or discontinuation 2
• Measuring testosterone at inconsistent times: For transdermal preparations, while timing is flexible, consistency in measurement timing helps with interpretation 1