Foundations before dose, tools, or optimisation
Testosterone Replacement Therapy (TRT)
TRT is medical testosterone given to restore levels to a normal, functional range in people whose bodies no longer produce enough on their own.
It is not bodybuilding, not a shortcut to fitness, and not a cure-all—but when used correctly, it can restore baseline physiology that has fallen below normal.
New here? Start at the Hormones & health basics overview to understand the full foundation before tools or dosing.
What TRT actually is
Testosterone Replacement Therapy replaces deficient testosterone with an external source—most commonly via injections, but also gels, creams, or pellets.
The goal is simple: restore testosterone to a level where normal biological functions work again.
- Energy and fatigue regulation
- Libido and sexual function
- Mood and cognitive stability
- Muscle mass and strength maintenance
- Bone density and red blood cell production
TRT replaces missing hormone—it does not “boost” you above normal when done correctly.
Who TRT is actually for
TRT is intended for people with:
- Persistently low testosterone on properly timed bloodwork
- Symptoms that match hormonal deficiency
- No reversible lifestyle or medical cause left unaddressed
Low numbers alone aren’t enough. Symptoms, repeat labs, and context matter. This is why understanding bloodwork basics for TRT comes before dose decisions.
What TRT is not
- Not a fat-loss drug
- Not guaranteed motivation or discipline
- Not a replacement for sleep, nutrition, or training
- Not a free pass to ignore health markers
TRT improves capacity. You still have to use it.
Common TRT delivery methods
Injections (most common)
- Testosterone cypionate or enanthate
- Predictable, adjustable, cost-effective
- Requires consistent injection timing
Topicals (gels/creams)
- Daily application
- Variable absorption
- Risk of transfer to others
Pellets
- Long-acting implants
- Limited dose flexibility
- Minor surgical procedure
Why bloodwork is non-negotiable
TRT affects more than testosterone. Monitoring keeps therapy safe and sustainable.
- Testosterone & estradiol balance
- Red blood cell levels (hematocrit)
- Lipids and cardiovascular risk
- Liver and kidney markers
Before changing anything, understand how to read common lab markers and standardise timing with the pre-injection bloodwork checklist.
Where tools fit (and where they don’t)
Tools help with accuracy and planning—but they don’t decide whether TRT is right for you.
- Use the free testosterone calculator to understand usable testosterone when SHBG skews totals.
- Use the TRT dose calculator only after labs and symptoms justify a plan.
If you’re ready to think about schedules and amounts, start with dose planning basics before changing anything.
Common questions
Is TRT for life?
Often, yes. Once endogenous production is suppressed, stopping TRT usually returns you to baseline—or lower.
Will TRT shut down natural testosterone?
Yes. External testosterone suppresses natural production. This is expected and managed—not a surprise.
Does TRT cause infertility?
TRT suppresses sperm production. Fertility-preserving strategies exist but must be planned intentionally.
Key takeaways
- TRT replaces deficient testosterone—it doesn’t create superhuman results.
- Symptoms + labs determine suitability, not numbers alone.
- Bloodwork is mandatory, not optional.
- TRT supports effort—it does not replace it.
Go back to the Hormones & health basics overview or move into dose planning basics once your labs and symptoms are clear.