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TRT, Explained by Someone Who Isn't Selling It.

Low testosterone, every delivery method, every lab marker, every side effect and what it all costs. One editor, not a clinic, with every clinical claim linked to the guideline or trial it comes from.

Quick check: where does your total testosterone sit for your age?

Model from the harmonized 264 to 916 ng/dL range (Travison 2017), 1% a year decline from 40. Context for a conversation with a clinician, not a diagnosis. Full tool and sources.

  • 41 sourced entries
  • 5 hubs plus a glossary
  • 7 free tools
  • 0 sponsors, clinics or products

Most Read.

The entries readers open first.

All entries →
Side effectsTRT Side Effects: What to Expect and How to ManageStarting testosterone replacement therapy is a significant decision, and understanding what your body may experience during treatment is just as important as…Jun 24, 2026Read the entrySide effectsTRT and Muscle Loss: What Men Need to KnowLosing muscle as you age is one of the most frustrating experiences a man can face. You may be eating well, hitting the gym consistently, and still watching…Jun 22, 2026Read the entryLow TTRT and Brain Fog: Can Testosterone Fix It?If you find yourself staring at a screen unable to form a coherent thought, forgetting words mid-sentence, or struggling to concentrate through even simple…Jun 19, 2026Read the entryTRTTRT and Weight Loss: What Men Need to KnowMany men starting testosterone replacement therapy hope it will help them shed unwanted body fat, particularly the stubborn belly weight that seems to…Jun 17, 2026Read the entryLow TTRT and Sleep: How Low Testosterone Disrupts RestPoor sleep and low testosterone share a complicated relationship that most men never fully understand. Many men struggling with chronic fatigue, restless…Jun 17, 2026Read the entryLow TTRT and Sleep: How Low Testosterone Disrupts RestPoor sleep and low testosterone share a complicated relationship that most men never fully understand. Many men struggling with chronic fatigue, restless…Jun 17, 2026Read the entryLow THow to Improve Low Testosterone During a Busy WeekFeeling drained, losing muscle, or noticing low libido while juggling a packed schedule is common. You do not always need weeks off or a full medical regimen…Jun 17, 2026Read the entryTRTHow to Decide If TRT Is Right for YouDeciding whether to start testosterone replacement therapy (TRT) is a clinical and personal choice. Many men experience fatigue, low libido, muscle loss, brain…Jun 15, 2026Read the entry

Reference Chart

Total Testosterone by Age.

Harmonized 2.5th to 97.5th percentile band for healthy nonobese men (264 to 916 ng/dL at ages 19 to 39, Travison 2017), with a 1 percent per year decline applied from age 40, a conservative figure from longitudinal cohorts. A model, not a lab's reference interval. Hover or tap any age for the numbers.

2.5th to 97.5th percentile bandMedian, steadyMedian, decliningBand edges
Total testosterone reference band by age, 20 to 80Shaded percentile band with a median line. Flat from 20 to 40, then declining about one percent a year. Hover for exact values.
Age along the bottom, total testosterone in ng/dL up the side. Tap or hover for the values at any age. Sources and model assumptions are on thepercentile tool page.

Five Ways to Take Testosterone, Side by Side.

The neutral comparison a clinic page won't give you. Each name links to its entry.

Full comparison →
MethodHow oftenLevel patternNeedlesFertilityCost
InjectionsWeekly or twice weeklyPeak then trough between shotsYesSuppressesLowest (generic)
Gel or creamEvery daySteady if applied consistentlyNoSuppressesModerate to high
Oral capsulesTwice daily with foodRises and falls within the dayNoSuppressesHigh (brand only)
PelletsEvery 3 to 6 monthsHigh early, fading to the next implantOffice procedureSuppressesProcedure fee each time
Nasal gel2 to 3 times dailyShort pulses with each doseNoLess suppression in small studiesHigh (brand only)

All external testosterone suppresses the pituitary signals for sperm production. Cost cells are relative; the cost estimator puts numbers on them with your own assumptions.

Glossary

Every Term, Defined in a Paragraph.

Aromatase, ester, SHBG, trough. Short definitions with a source each, written to be read in thirty seconds.

Open the glossary →

Glossary terms are written in WordPress under the "Glossary" category and the first ten appear here automatically.

Common Questions About TRT.

Short answers, each linking to the entry that goes deeper.

What is testosterone replacement therapy?
Testosterone replacement therapy, or TRT, is prescription testosterone given to men whose own production is low and who have symptoms, confirmed by repeated morning blood tests. It is delivered as injections, gels, oral capsules, pellets or nasal gel, and it is monitored with periodic lab work.
What testosterone level is considered low?
Guidelines use repeated morning total testosterone below roughly 264 ng/dL, together with symptoms, as the working definition in healthy nonobese men. The threshold, the assay and the time of day all matter, which is why one reading is never enough.
Is TRT safe?
TRT has a defined set of side effects, the most common being a rise in red blood cell count, and a set of monitoring rules built around them. Large trials in the 2020s clarified cardiovascular questions that were open for a decade. The side effects hub covers each one with the evidence behind it.
Does TRT affect fertility?
Yes. External testosterone suppresses the pituitary signals that drive sperm production, so sperm counts fall, often to zero, while on therapy. Men who want children usually pair TRT with hCG, use an alternative such as clomiphene or enclomiphene, or bank sperm first.
How much does TRT cost?
Generic injectable testosterone is inexpensive; the cost of TRT is mostly the provider, the labs and the delivery method. Cash prices range from under a hundred dollars a month at some online clinics to several hundred for brand-name gels or oral capsules. The cost estimator tool shows a yearly range with its assumptions.
Can I get TRT online?
In most US states, yes, through telehealth clinics that order labs, hold a video consultation and ship medication from a partner pharmacy. State rules on controlled-substance prescribing by telehealth differ and change, which the cost and access hub tracks.
Who writes TRT Foundation?
Tejanshu Jaluthria, an independent editor. He is not a clinician. Every clinical claim links its source so you can take it to your own doctor.
Is TRT Foundation a nonprofit or a clinic?
Neither. It is an independent, ad-supported reference site. It does not sell, prescribe or recommend any product or provider.