What is the starting dose for testosterone replacement therapy?

Starting Dose for Testosterone Replacement Therapy

For testosterone replacement therapy in hypogonadal males, the recommended starting dose is 50-100 mg weekly for injectable testosterone cypionate/enanthate, or 50 mg daily for transdermal gel formulations. 1, 2, 3

Injectable Testosterone Starting Doses

• Testosterone Cypionate/Enanthate (IM):

  • Initial dose: 50-100 mg weekly OR 100-200 mg every 2 weeks 1, 2
  • FDA-approved dosing range: 50-400 mg every 2-4 weeks 1, 2
  • Target serum testosterone level: 450-600 ng/dL 4

• Testosterone Undecanoate (long-acting IM):

  • Initial dose: 750 mg initially, followed by 750 mg after 4 weeks, then 750 mg every 10 weeks 3
  • Advantages: Fewer injections, more stable testosterone levels 3
  • Note: Has restricted access in the United States 3

Transdermal Testosterone Starting Doses

• Testosterone Gels (1%):

  • Initial dose: 50 mg daily applied to skin of back, abdomen, upper thighs, or arms 3
  • Dose range: 50-100 mg daily 3

• Testosterone Gels (1.62%):

  • Initial dose: 20.25-40.5 mg daily 3
  • Dose range: 20.25-81 mg daily 3

• Testosterone Solutions:

  • Axiron 2% solution: 30 mg per actuation, initial dose 30-60 mg daily 3
  • Fortesta 2% gel: 10 mg per actuation, initial dose 40 mg daily 3

Monitoring and Dose Adjustment

1. Initial Monitoring:

   • Check testosterone levels 2-3 months after starting therapy 3, 4
   • For injectable testosterone: Measure levels midway between injections, targeting 500-600 ng/dL 3, 4
   • For transdermal preparations: Levels can be measured at any time (peak values occur 6-8 hours after application) 3

2. Ongoing Monitoring:

   • Once stable levels achieved, monitor every 6-12 months 3
   • Monitor hematocrit, PSA, and symptoms every 3 months for the first year 4
   • Adjust dose if testosterone levels fall outside target range of 450-600 ng/dL 4

Safety Considerations

• Cardiovascular Risk:

  • FDA required labeling change in 2015 regarding possible increased risk of heart attack and stroke 3
  • Injectable testosterone may be associated with greater cardiovascular risk than gels due to fluctuating levels 3

• Hematocrit Management:

  • Monitor closely as testosterone stimulates erythropoiesis 3
  • Consider dose reduction or formulation change if hematocrit exceeds 50% 4
  • Discontinue therapy if hematocrit exceeds 54% 4

• Formulation Selection Considerations:

  • Injectable formulations: More economical, less frequent dosing, but greater fluctuations in testosterone levels 3
  • Transdermal formulations: More stable levels, easier application, but potential for transfer to others and higher cost 3

Pitfalls to Avoid

1. Starting with too high a dose, which may lead to supraphysiologic levels and increased side effects
2. Inadequate monitoring of testosterone levels, hematocrit, and PSA
3. Failing to consider contraindications: active prostate/breast cancer, hematocrit >50%, severe untreated sleep apnea, uncontrolled heart failure 4
4. Not discussing fertility implications with patients desiring future fertility 4
5. Overlooking the need for dose adjustments based on individual response and adverse effects

The choice between injectable and transdermal formulations should consider patient preference, cost considerations, and risk profile, with recent evidence suggesting that subcutaneous administration may offer advantages over intramuscular injection for some patients 5, 6.