Hormones & Neuropeptides

Testosterone

Also known as: TRT · Testosterone Replacement Therapy · Testosterone Cypionate · Testosterone Enanthate

The foundational male hormone — the complete TRT guide with optimal levels.

Half-Life
Testosterone Cypionate: ~8 days. Testosterone Enanthate: ~4.5 days
Administration
Subcutaneous injection
Category
Hormones & Neuropeptides
Citations
2 studies

What is Testosterone?

Testosterone is the primary male sex hormone and anabolic steroid. Testosterone Replacement Therapy (TRT) is the medical administration of testosterone to restore optimal levels in men with hypogonadism or age-related testosterone decline. TRT is one of the most impactful health interventions available for men with low testosterone, with profound effects on body composition, energy, cognition, libido, and longevity.

Mechanism of Action

Testosterone binds to androgen receptors throughout the body, activating anabolic signaling in muscle (protein synthesis, nitrogen retention), bone (density), brain (cognition, mood, libido), cardiovascular system (red blood cell production, cardiac function), and metabolic tissue (insulin sensitivity, fat distribution).

Testosterone Dosing Protocol

TRT: 100–200 mg/week testosterone cypionate or enanthate subcutaneous or intramuscular. Target total testosterone: 800–1,200 ng/dL (NOT the pathetically low 'normal' range of 300–1,000 ng/dL). Inject 2–3 times per week for stable levels. Monitor estradiol, hematocrit, PSA, and lipids.

Administration Routes
Subcutaneous injectionIntramuscular injectionTopical gel/creamPellet implant
Half-Life
Testosterone Cypionate: ~8 days. Testosterone Enanthate: ~4.5 days

Want a personalized protocol? Tell PepBot your goals, health status, and experience level for a custom Testosterone protocol.

Testosterone Benefits

Restored energy and vitality
Increased lean muscle mass
Reduced body fat
Improved libido and sexual function
Enhanced cognitive function and mood
Improved bone density
Cardiovascular benefits (at physiological levels)
Improved insulin sensitivity

Side Effect Profile

Estrogen conversion (requires monitoring and possible AI), polycythemia (elevated hematocrit — donate blood regularly), testicular atrophy (add HCG to preserve), potential hair loss (DHT-sensitive individuals), acne. Suppresses natural testosterone production (expected on TRT).

Testosterone Stacking Guide

Testosterone works synergistically with these compounds. Click any to learn more, or ask PepBot to build you a complete stack.

Research & Citations

1
Testosterone therapy in men with hypogonadism: an Endocrine Society Clinical Practice Guideline
Journal of Clinical Endocrinology & Metabolism · 2018
2
Testosterone and cardiovascular risk: the TRAVERSE trial
New England Journal of Medicine · 2023

Frequently Asked Questions about Testosterone

What testosterone level should I target on TRT?
Target 800–1,200 ng/dL total testosterone — NOT the pathetically low 'normal' range of 300–1,000 ng/dL that most labs use. Free testosterone should be 20–30 pg/mL. Most men feel optimal at 900–1,100 ng/dL. The 'normal' range includes men in their 80s and men with chronic illness — it is not an optimal range for a healthy adult male.
What blood tests do I need on TRT?
Essential TRT monitoring: Total and free testosterone (target 800–1,200 ng/dL), estradiol (E2, target 20–30 pg/mL), hematocrit (keep under 52%), PSA (baseline and annual), lipid panel, CBC, CMP. Test at 6–8 weeks after starting or changing dose, then every 3–6 months once stable. Services like Marek Health or Defy Medical specialize in TRT monitoring.

Still have questions about Testosterone?

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