Which testosterone ester, testosterone (T) enanthate, cypionate, or propionate, has the least dihydrotestosterone (DHT) conversion for a male patient trying to preserve hair while on testosterone replacement therapy (TRT)?

DHT Conversion and Testosterone Esters: The Evidence Shows No Difference

All three testosterone esters—enanthate, cypionate, and propionate—convert to DHT at identical rates because they are simply delivery vehicles for the same bioidentical testosterone molecule. Once the ester is cleaved by esterases in the bloodstream, you're left with pure testosterone regardless of which ester was attached, and this testosterone undergoes 5α-reductase conversion to DHT at the same rate in target tissues 1.

Why the Ester Doesn't Matter for DHT Conversion

The fundamental biochemistry is straightforward:

• Testosterone esters are prodrugs that release free testosterone after enzymatic cleavage of the ester side chain 2, 1
• The ester only affects pharmacokinetics (how quickly testosterone is released and how long it lasts in circulation), not the biochemical properties of the testosterone molecule itself 3, 2
• 5α-reductase enzymes convert testosterone to DHT in peripheral tissues (scalp, prostate, skin) at rates determined by local enzyme expression, not by which ester delivered the testosterone 1, 4

The three esters differ only in their release profiles:

• Testosterone propionate: Peaks at 24-48 hours, returns to baseline by 3-4 days 2
• Testosterone enanthate/cypionate: Peak at 2-5 days, return to baseline by 10-14 days 3, 5
• All produce identical free testosterone once the ester is cleaved, which then undergoes identical peripheral conversion to DHT 1

The Real Issue: Total Testosterone Exposure

What matters for DHT-related hair loss is your total testosterone exposure and peak levels, not which ester you use 1, 4. Higher testosterone levels mean more substrate available for 5α-reductase to convert to DHT in scalp follicles.

Practical Implications:

• Injectable testosterone (any ester) produces fluctuating levels with supraphysiologic peaks in the first 2-5 days after injection, during which DHT conversion is maximized 3, 5
• These peak levels can be 2-3 times the mid-normal range, providing excessive substrate for DHT formation 3
• Transdermal preparations (gels, patches) maintain more stable day-to-day testosterone levels without supraphysiologic peaks, potentially reducing peak DHT exposure 3, 5

Evidence-Based Recommendations for Hair Preservation

If hair preservation is your primary concern, transdermal testosterone gel is superior to any injectable ester because it avoids the supraphysiologic peaks that drive excessive DHT conversion 3, 5.

Specific Algorithm:

1. First-line: Transdermal testosterone gel 1.62% at 40.5 mg daily targeting mid-normal testosterone levels (450-600 ng/dL) to minimize DHT substrate availability 3, 5

2. If cost prohibits gel use and you must use injections:

   • Use smaller, more frequent doses (e.g., 50 mg weekly rather than 200 mg every 2 weeks) to minimize peak-to-trough fluctuations 3, 5
   • Enanthate and cypionate are interchangeable for this purpose—choose based on availability and cost 3, 6
   • Propionate requires even more frequent injections (every 2-3 days) due to its shorter half-life, making it impractical 2

3. Concurrent 5α-reductase inhibitor therapy:

   • Finasteride 1 mg daily blocks Type II 5α-reductase, reducing scalp DHT by approximately 70% regardless of testosterone source 4
   • This is the most effective intervention for hair preservation during testosterone therapy, far more important than ester selection 4
   • Be aware that finasteride may cause sexual side effects in 2-4% of men, and these can persist in rare cases even after discontinuation 4

Critical Caveats

The belief that different esters produce different DHT levels is a common misconception in bodybuilding and online forums, but it has no biochemical basis 1. The ester is cleaved within hours to days, leaving identical free testosterone that undergoes identical peripheral metabolism 2, 1.

Your testosterone dosing strategy matters far more than ester selection:

• Avoid supraphysiologic dosing (keeping levels >600 ng/dL) as this maximizes DHT substrate 5, 6
• Target mid-normal range (450-600 ng/dL) to balance symptom relief with hair preservation 5, 6
• Monitor testosterone levels midway between injections to ensure you're not spending excessive time in supraphysiologic ranges 3, 5

If you're using testosterone for non-medical purposes (bodybuilding, performance enhancement), understand that any supraphysiologic testosterone dosing will accelerate androgenetic alopecia in genetically susceptible individuals, regardless of ester choice 4. The only effective mitigation is 5α-reductase inhibition with finasteride or dutasteride 4.