How Testosterone Enanthate Affects DHT

Testosterone is converted to dihydrotestosterone (DHT) by the enzyme 5-alpha reductase, which exists in two isoforms:

1. Type I: Found in sebaceous glands and skin. Responsible for the large DHT increase seen with transdermal testosterone (creams and gels), because testosterone passes through 5-alpha reductase-rich skin tissue before reaching systemic circulation.
2. Type II: Concentrated in hair follicles, the prostate, and genital tissue. This isoform drives the local DHT production responsible for androgenetic alopecia and prostate growth.

When testosterone enanthate is injected intramuscularly, it bypasses the skin entirely. The testosterone enters systemic circulation from the muscle depot and is converted to DHT at a lower overall rate than transdermal formulations. A meta-analysis found that intramuscular testosterone increased serum DHT by 2.20 times baseline, compared to 5.46 times baseline for transdermal formulations.

DHT binds the androgen receptor approximately five times more strongly than testosterone. In tissues with high 5-alpha reductase activity (scalp, prostate, skin), this amplified androgenic signal drives tissue-specific effects: follicle miniaturisation in genetically susceptible hair, prostate growth, and sebum production.

Replacement doses (100-200 mg/week, intramuscular):

• Serum DHT typically rises to 2.0-2.5x baseline
• If pre-TRT DHT was 40 ng/dL, expect approximately 70-100 ng/dL on injections
• The increase stabilises within 6-12 weeks

Supraphysiological doses (300-600+ mg/week):

• DHT rises proportionally with dose, potentially reaching 3-5x baseline
• Higher substrate availability means more conversion despite enzyme saturation
• The increase can exceed the reference range (30-85 ng/dL) substantially

Transdermal testosterone (creams/gels, for comparison):

• DHT rises to 4.0-6.0x baseline at equivalent testosterone levels
• First-pass skin metabolism converts a large fraction to DHT before systemic absorption
• A man with baseline DHT of 40 ng/dL may see 160-240 ng/dL on cream

Timing: DHT rises in parallel with testosterone levels. On enanthate, expect a gradual increase over the first 4-8 weeks as steady-state testosterone is reached.

Baseline: Request DHT alongside your standard pre-TRT panel (total testosterone, free testosterone, oestradiol, SHBG, CBC). Most panels omit DHT by default; you need to ask for it specifically.

First check: 6-8 weeks after starting TRT, drawn at trough (before your next injection). This captures the initial DHT response to your protocol.

Ongoing: Every 6 months if your hairline is stable and you have no prostate symptoms. More frequently (every 3 months) if you notice hair thinning, increased acne, or urinary symptoms.

When to add extra checks:

• Switching delivery method (especially from injections to cream, or vice versa)
• Dose increase
• Starting or stopping a 5-alpha reductase inhibitor (finasteride, dutasteride)
• New scalp hair shedding or frontal recession

If DHT is elevated but you have no symptoms (no hair loss, no prostate issues, no severe acne):

• No intervention needed. Elevated DHT on TRT is expected and not inherently harmful without symptoms or genetic susceptibility
• Continue monitoring every 6 months

If DHT is elevated and you are experiencing hair thinning:

• Switch from transdermal to injectable testosterone if applicable (reduces DHT by approximately 60%)
• Consider finasteride 1 mg daily (reduces scalp DHT by approximately 64%, serum DHT by approximately 70%)
• Topical minoxidil 5% provides additive hair protection through a separate mechanism
• Photograph your hairline for objective tracking

If DHT is elevated with prostate symptoms (urinary hesitancy, frequency, nocturia):

• Refer to a urologist for PSA testing and prostate assessment
• Finasteride or dutasteride may be indicated for both prostate and hair protection
• Do not self-medicate; prostate symptoms require medical evaluation

Important: Do NOT combine finasteride with nandrolone. Blocking 5-alpha reductase prevents nandrolone's conversion to the weaker dihydronandrolone (DHN), paradoxically increasing its androgenic effects at the follicle and prostate.