How long does it take for testosterone to leave the system of an athlete who was transitioning from female to male but has reversed their decision?

Testosterone Clearance After Discontinuation in Female-to-Male Transition Athletes

After discontinuing testosterone therapy in female-to-male transitioning athletes, it typically takes 3-4 months for testosterone levels to return to female reference ranges, though physiological advantages may persist for 2-3 years or longer.

Physiological Timeline After Testosterone Discontinuation

Immediate Effects (0-3 months)

• Serum testosterone levels begin to decline shortly after discontinuation
• Laboratory values typically return to baseline within 3 months after discontinuation of hormone therapy 1
• Hemoglobin and hematocrit levels gradually decrease toward female reference ranges

Medium-Term Effects (3-12 months)

• Voice changes remain permanent (irreversible effect of testosterone) 1
• Body and facial hair changes are largely irreversible even after testosterone cessation 1
• Menstruation may resume within several months, though timing varies individually
• Fertility may begin to return, though timeline is variable 2

Long-Term Effects (1-3+ years)

• Muscle mass and strength advantages persist but gradually decline
• After 3 years of testosterone discontinuation, most physical performance parameters approach female reference ranges 3
• Some advantages in muscle strength and power may persist beyond 3 years, particularly for upper body exercises like push-ups 3

Athletic Performance Considerations

The timeline for fair competition eligibility should consider:

1. Physiological advantages: Testosterone therapy in transgender men increases:

   • Muscle mass and strength (15% increase in quadriceps cross-sectional area) 1
   • Thigh muscle volume and radiological density (6% increase) 1
   • Performance in strength exercises (push-ups, sit-ups) 1, 3

2. Persistence of advantages:

   • Physical performance advantages may persist for 2+ years after testosterone discontinuation 3
   • While running times and sit-up performance return to female reference ranges within 2-4 years, push-up performance may maintain an advantage even after 4 years 3

Medical Monitoring Recommendations

• Monitor testosterone levels at 3 months post-discontinuation to confirm return to female reference range (typically <50 ng/dL) 4
• Evaluate hematocrit and hemoglobin levels, which should normalize within 3 months 1
• Consider bone density assessment, as cessation of testosterone without estrogen replacement may impact bone health 1

Important Caveats and Considerations

• Individual variation: The timeline for testosterone clearance and physiological changes varies between individuals
• Evidence limitations: Most studies are small, uncontrolled, and of short duration 3
• Irreversible changes: Some testosterone-induced changes (voice deepening, facial/body hair) remain permanent regardless of time since discontinuation 1
• Athletic context: The 3-month laboratory normalization period does not necessarily equate to elimination of all performance advantages

Clinical Implications

For sports governing bodies determining eligibility, a minimum waiting period of 2-3 years after testosterone discontinuation would be most appropriate based on current evidence to ensure fair competition, as this is when most (but not all) physiological advantages diminish significantly 3.