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Reviewed by MyPeptideMatch Editorial TeamLast reviewed February 2026Updated February 2026

Testagen Dosing Protocol: 20 mg Vial — Testicular Bioregulator & Testosterone Support Guide

Testagen (Lys-Glu-Asp-Gly tetrapeptide) Russian testicular bioregulator dosing guide — Leydig cell gene normalization for testosterone production optimization and male reproductive aging support.

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Quickstart highlights

Testagen (Lys-Glu-Asp-Gly, KEDG) is a tetrapeptide bioregulator from Khavinson's group targeting testicular Leydig and Sertoli cells.

  • Concentration: 2 mg/mL (20 mg + 10 mL bac water).
  • At 2 mg/mL: 200 µg = 10 units daily x 10 days.
  • Targets Leydig cell StAR, LH receptor, and steroidogenic enzyme gene normalization.
  • Combine with HCG for synergistic Leydig cell stimulation (bioregulator + LH mimic).
  • Monitor total testosterone, LH, and FSH at baseline and 3 months post-course.

Dosing table

For educational reference only. Your prescribing provider may adjust doses based on your clinical profile and response.

WeekDose (µg)UnitsFrequencyNotes
1-2 (10-day course)20010Once daily (morning)200 µg — 10 units; 10-day intensive course; 20 mg vial = 100 doses
Maintenance20010Every other day200 µg EOD — testosterone optimization maintenance

Reconstitution steps

  1. Reconstitute in 2.5 mL bac water portions; inject slowly down vial wall.
  2. Swirl gently until dissolved. Final concentration: 2 mg/mL.
  3. Label with date; refrigerate 2–8 °C. Use within 28 days.

Supplies needed

10_day-week plan

  • 1 vial
  • 10 syringes
  • 2 mL bac water
  • 10 alcohol swabs
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Protocol overview & cycle notes

Normalize Leydig cell gene expression for testosterone biosynthesis and spermatogenic support through the Testagen tetrapeptide testicular bioregulator 10-day intensive course, targeting natural testosterone optimization in aging males.

Off-cycle: 4–6 months between courses; recheck testosterone before each course.

Storage & handling

Lyophilized: store below 25 °C. Reconstituted: refrigerate 2–8 °C; use within 28 days.

Injection & tracking tips

  • Morning injection — testosterone production peaks in morning hours; Testagen complements this circadian pattern.
  • Testagen may be combined with HCG (LH mimic) for synergistic Leydig cell stimulation.
  • Not a replacement for TRT in clinical hypogonadism; rather a natural testosterone support bioregulator.

Tracking

Logging helps you and your provider spot patterns and adjust dose or timing.

  • Serum testosterone (total and free), LH, FSH at baseline and 3 months post-course.
  • Track morning energy, libido, and muscle recovery quality weekly (0–10 scale).
  • Semen analysis at baseline and 6 months if fertility is a goal.
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How this works & references

Testagen (Lys-Glu-Asp-Gly, KEDG) is a tetrapeptide bioregulator from Khavinson's group targeting testicular Leydig and Sertoli cells. Proposed mechanisms: normalization of StAR (steroidogenic acute regulatory protein) gene expression, which is rate-limiting for testosterone biosynthesis; restoration of LH receptor expression in aging Leydig cells; normalization of 3β-HSD and CYP17A1 enzyme expression for androgen synthesis. Russian clinical applications include age-related testosterone decline (andropause), subfertility support, and post-TRT recovery. Testagen is the testicular bioregulator analogue of Cortagen (brain) and Cardiogen (heart).

Sources

  • Source: Khavinson VK et al. — Short peptide bioregulators. Ann N Y Acad Sci. 2010;1207:66-75

Frequently asked questions

Can Testagen restore testosterone levels in men with low-normal T?
Testagen is most appropriate for men with age-related testosterone decline in the low-normal range (8–14 nmol/L or 230–400 ng/dL) where Leydig cell capacity is partially preserved. It is a gene expression normalizer — it cannot restore testosterone in men with severely damaged or absent Leydig cells (primary hypogonadism, after orchidectomy). For borderline low T where Leydig cells are functional but underperforming, Testagen may normalize gene expression to improve output.
Does Testagen affect fertility?
Testagen targets both Leydig (testosterone) and potentially Sertoli cell gene expression. Improved intratesticular testosterone from Leydig normalization would support spermatogenesis. For subfertile men with borderline testosterone and normal LH/FSH, Testagen may provide marginal benefit. Men with fertility as a primary goal should combine with HCG+HMG under fertility specialist care.
How does Testagen compare to Tongkat Ali for testosterone support?
Tongkat Ali (Eurycoma longifolia) reduces SHBG (increasing free testosterone) and contains eurycomanone that may inhibit SHBG-testosterone binding. Testagen targets Leydig cell gene expression normalization at the biosynthesis level. Both are 'natural testosterone support' approaches but through different mechanisms — they could be complementary in comprehensive andropause protocols.
Can Testagen be used after TRT to restore natural testosterone production?
After TRT, hypothalamic-pituitary suppression and Leydig cell atrophy require HCG (acute stimulation) and SERM therapy (HPG axis restoration). Testagen, targeting Leydig cell gene expression normalization, could be a rational adjunct during the post-TRT recovery period to support Leydig cell functional restoration alongside HCG.
Is Testagen safe for men with prostate cancer history?
Testosterone-stimulating interventions (including Testagen) are generally contraindicated in men with active or recent androgen-sensitive prostate cancer. This is a relative contraindication — discuss with your oncologist. Post-radical prostatectomy patients with no evidence of disease may have different risk-benefit calculations.

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This content is for informational purposes only and does not constitute medical advice. Consult a licensed healthcare provider before starting any peptide therapy. Dosing and protocols may vary by formulation and prescriber.

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