What adjustment should be made to a testosterone regimen of 100mg every 2 weeks for a patient with low testosterone levels, which are below the normal range of 8.4-28.8 ng/dL, and who experienced high levels when dosed at 100mg weekly?

Testosterone Dose Adjustment for Subtherapeutic Levels

Increase the dose to 100mg every 10 days (or 70mg weekly), which provides an intermediate dosing frequency between the current every-2-week regimen that is too low and the weekly regimen that was too high.

Rationale for Dose Selection

The current situation requires a dose that falls between 100mg every 2 weeks (50mg/week equivalent) and 100mg weekly. The optimal approach is to shorten the dosing interval to 100mg every 10 days, which delivers approximately 70mg per week—a middle ground between the two extremes. 1, 2

• The FDA-approved dosing range for testosterone cypionate is 50-400mg every 2-4 weeks, allowing flexibility in both dose and interval 3
• More frequent dosing (every 10 days vs every 14 days) provides more stable testosterone levels with smaller peak-to-trough fluctuations 1, 2
• This approach avoids the supraphysiological peaks that occurred with 100mg weekly while maintaining adequate trough levels 1

Alternative Dosing Strategy

If the every-10-day schedule is impractical, consider 75mg weekly as an alternative, which provides slightly more testosterone than the 70mg/week equivalent of the 100mg every 10 days regimen. 2, 4

• Weekly dosing of 50-100mg provides more stable testosterone levels compared to biweekly administration 2
• The 75mg weekly dose has been validated in clinical trials as an effective intermediate dose 4
• This allows for easier self-administration and more consistent serum levels 4

Target Testosterone Levels and Monitoring

Target mid-normal testosterone levels of 450-600 ng/dL (or 500-600 ng/dL per some guidelines) when measured midway between injections. 1, 2

• Measure testosterone levels 2-3 months after this dose change 1, 2, 5, 6
• For injections given every 10 days, draw levels on day 5 after injection 1
• For weekly injections, draw levels on days 3-4 (midway between injections) 1, 2
• Peak levels occur 2-5 days after injection, with return to baseline by days 10-14 1

Critical Monitoring Parameters

Beyond testosterone levels, monitor for dose-dependent adverse effects:

• Hematocrit/hemoglobin at each visit—withhold treatment if hematocrit exceeds 54% 1, 2, 5, 6
• Injectable testosterone carries a 43.8% risk of erythrocytosis compared to 15.4% with transdermal preparations 2
• PSA and digital rectal examination in men over 40 years 1, 5, 6
• Assess symptomatic response, particularly sexual function and libido 1

Why Not Other Dose Adjustments?

Do not simply increase to 100mg every 12 days or reduce to 75mg every 2 weeks, as these approaches fail to optimize the dosing interval:

• The every-2-week interval creates excessive fluctuation between supraphysiological peaks and subtherapeutic troughs 1, 2
• More frequent administration (every 7-10 days) provides superior pharmacokinetic stability 1, 2
• The goal is to minimize the peak-to-trough ratio while achieving mid-normal average levels 1, 2

Common Pitfall to Avoid

Do not draw testosterone levels at the peak (days 2-5) or at the trough (days 13-14), as this will lead to inappropriate dose adjustments. 1

• Peak measurements show supraphysiological levels that don't reflect average exposure and may lead to inappropriate dose reduction 1
• Trough measurements may show subtherapeutic levels that could lead to unnecessary dose escalation 1
• Always measure midway between injections to capture representative levels 1, 2