In an adult transgender woman on eight months of feminizing hormone therapy with low‑normal testosterone for the first five months and low testosterone for the last three months, would irreversible penile atrophy occur?

Penile Atrophy After 8 Months of Feminizing HRT

Direct Answer

Eight months of feminizing hormone therapy with the testosterone levels you describe (300-400 ng/dL for 5 months, then 100-200 ng/dL for 3 months) will likely cause some degree of penile shrinkage, but complete irreversibility is uncertain because your testosterone suppression has been suboptimal for most of the treatment period. 1

Understanding the Mechanism of Penile Changes

• Feminizing hormone therapy causes penile tissue changes through testosterone suppression to female-range levels (<50 ng/dL) combined with estradiol exposure, which directly affects genital tissue structure and reduces erectile function 1
• Anti-androgen therapy produces testicular atrophy as a documented and expected effect 1
• The combined hormonal effects result in decreased libido and erectile capacity, which contributes to structural penile tissue changes over time 1

Your Specific Testosterone Levels Matter

• Your testosterone levels have remained significantly above the target range for feminizing therapy throughout your 8-month course 1, 2
• The target testosterone level for feminizing hormone therapy is <50 ng/dL (the female range), not 100-400 ng/dL 3, 1, 2
• At 300-400 ng/dL during the first 5 months, you maintained testosterone in the low-normal male range (normal male range is 300-1,000 ng/dL), which provides minimal feminizing effect 2
• Even at 100-200 ng/dL during the last 3 months, your testosterone remained 2-4 times higher than the therapeutic target 1, 2
• Up to 25% of transgender women on feminizing therapy fail to achieve adequate testosterone suppression, which appears to be your situation 4, 5

Timeline and Degree of Penile Changes

• Reduced erectile function typically begins within the first few months of feminizing hormone therapy when testosterone is adequately suppressed 1
• Anatomical and functional changes generally progress over 12-36 months as hormone levels stabilize within the female range 1
• Because your testosterone suppression has been inadequate, you have likely experienced less penile shrinkage than would occur with properly dosed feminizing therapy 1, 5
• Clinical observations indicate that penile shrinkage occurs in transgender women receiving feminizing hormone therapy and is likely permanent while therapy continues long-term 1

Reversibility Considerations

• Hormone-induced structural changes in genital tissue (including penile shortening) are considered irreversible even after cessation of therapy, similar to irreversible changes such as voice deepening in masculinizing regimens 1
• However, the degree of irreversible change depends on the adequacy and duration of testosterone suppression—your suboptimal suppression may mean less permanent change has occurred 1
• Assuming all hormonal effects are reversible is inaccurate; structural genital alterations may persist despite hormone discontinuation 1

What You Should Know Going Forward

• If you continue feminizing therapy, your regimen needs optimization to achieve testosterone <50 ng/dL for effective feminization 1, 2
• Patients should be informed before initiating or continuing therapy that genital changes—including potential penile shrinkage—may occur, especially when future gender-affirming surgery (vaginoplasty) relies on penile tissue 1
• Discussing the possibility of preserving erectile function or genital size is important for individuals who prioritize these outcomes 1
• Failure to address surgical implications can affect tissue availability and surgical outcomes in later vaginoplasty procedures 1

Common Pitfalls in Your Situation

• Your current hormone regimen is not achieving therapeutic testosterone suppression 4, 5
• One study found that only the highest suppressing quartile of transgender women on spironolactone and estrogen could reliably achieve testosterone levels in the female range, while one quartile was unable to achieve any significant suppression 5
• Nonsuppressed testosterone levels are seen in up to a quarter of transgender women on gender-affirming feminizing hormonal treatment 4
• Multiple factors contribute to inadequate suppression, including medication dosing, patient adherence, and individual physiological variation 4