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Not medical advice. The Atlas is not a substitute for a clinician who can examine you.

The Testosterone Trials (T-Trials)

Coordinated 7-Trial Program in Older Men (Snyder et al., NEJM 2016 / JAMA Internal Medicine 2017)

Evidence grade 4 of 5, Strong. Read how the Atlas grades evidence.

7 human trials, about 7 studies, 790 participants men aged >=65 with serum T <275 ng/dL. The written rationale for this grade is still being prepared.

FDA
Independent NIA-funded RCT program (not a drug approval)

Reference only. Not medical advice.

What can go wrong

The cardiovascular sub-trial found a significant increase in non-calcified coronary plaque volume after one year of testosterone, a worrying imaging signal even though clinical events were too few to assess in a one-year, 790-man program.

This is something to take to a clinician. The Atlas can tell you what is known about the testosterone trials (t-trials) in general. It cannot tell you what is happening in your body, and the difference matters most for exactly the symptoms that bring people to this page.

The T-Trials were a set of seven coordinated, double-blind, placebo-controlled randomized trials in 790 men aged 65 and older with unequivocally low testosterone and symptoms. Funded by the National Institute on Aging and led by Peter Snyder, they tested testosterone gel against placebo for one year across sexual function, physical function, vitality, cognition, anemia, bone, and cardiovascular (coronary plaque). The findings were nuanced: clear sexual-function benefit, benefit for anemia and bone density, no meaningful benefit for vitality, walking, or cognition, and a concerning increase in coronary non-calcified plaque.

Seven coordinated trials that mapped exactly what testosterone does - and does not - do in older men.

What people take it for

What it is taken for. Approval, where it exists, covers only some of these.

  • Defining realistic expectations for TRT in older men
  • Separating evidence-based from hyped benefits
  • Guideline citation for symptom-specific prescribing
Sexual function
Significant improvement in sexual activity, desire, and erectile function vs placebo (modest effect size)
Anemia
Corrected anemia of otherwise unexplained and of known cause more often than placebo
Bone
Increased volumetric bone mineral density and estimated strength (spine > hip)

How it works

By raising serum testosterone in older men from below 275 ng/dL into the range typical of younger men and measuring outcomes domain by domain, the T-Trials isolated which symptoms attributed to 'low T' actually respond to replacement and which do not.

The honest mixed verdict

The T-Trials are the clearest demonstration that 'low T' symptoms are domain-specific. Testosterone reliably helped libido and erections, modestly. It did NOT make older men walk farther, feel less tired, or think more clearly - the very benefits most heavily marketed by 'low T clinics.' And the coronary-plaque finding was an alarm that TRAVERSE was later designed partly to address.

Safety in detail

This intervention involves significant physiological effects and requires evaluation and monitoring by a qualified physician. Self-administration without medical oversight carries documented health risks.

What people get wrong

  • Often saidTestosterone restores energy and vitality in older men

    ActuallyThe T-Trials found NO significant improvement in vitality or fatigue versus placebo - one of the most-marketed claims failed in a rigorous RCT.

  • Often saidTRT improves memory and cognition with age

    ActuallyThe Cognitive Function Trial found no benefit on memory or other cognitive measures.

Who profits, and who pushes back

Nobody is named here yet, because we have not done that work on this entry. Read that as unfinished. Somebody almost certainly sells this, and somebody almost certainly disputes it. Assume both until we have checked.

How we got here

Conceived to bring rigor to a field dominated by marketing, the T-Trials recruited from 12 U.S. sites starting in 2010. The coordinated design let one shared placebo-controlled population be analyzed across seven prespecified outcome domains, an unusually disciplined approach. NEJM published the first three trials in 2016; JAMA and JAMA Internal Medicine published the remaining four in 2017.

  1. 2009-2010NIA funds and launches the coordinated program
  2. 2010-2014Enrollment and 1-year treatment of 790 men
  3. 2016Sexual/physical/vitality results in NEJM
  4. 2017Cognition, bone, anemia, and cardiovascular results published

What the trials could not show

Limits of the studies themselves, as distinct from limits of the treatment.

  • Only one year of treatment; relatively small N per individual trial (limiting power for hard outcomes); enrolled symptomatic men with confirmed low T, so results do not apply to men with normal levels; gel formulation only; coronary-plaque result was an imaging surrogate, not clinical events.

What we do not know

  • Would benefits or the plaque signal grow beyond one year?
  • Do younger men or those with borderline levels respond differently?
  • Is the coronary-plaque finding clinically meaningful long-term?

At a glance

Design
7 coordinated double-blind RCTs, testosterone gel vs placebo, 1 year
N
790
Population
Men >=65, avg of two T levels <275 ng/dL, with symptoms
Funder
National Institute on Aging (NIH)
Lead
Peter J. Snyder, University of Pennsylvania
Duration
12 months treatment

What this entry does not yet cover

What follows is unfinished work on our side, not a finding about The Testosterone Trials (T-Trials). A short entry is not a safe entry.

  • Cost and market. We have not documented what it sells for or who sells it.
  • Supply chain. We have not mapped where it is made.
  • Who uses it. We have not documented the user groups.
  • What could change. No forward-looking summary yet.
  • How it compares. We have not set it against the alternatives.
  • Children and teenagers. We have not checked what is known about younger people.

Sources

The studies below are named and described, but not linked. You cannot open them from here and check our reading against them, which means this page is our summary of the literature rather than a document you can verify. Weigh it accordingly until the links exist.

The studies that matter

  • Sexual Function, Physical Function, Vitality Trials (Snyder et al., NEJM)2016

    Consistent benefit for sexual function; NO significant benefit for 6-minute walk distance or vitality (FACIT-Fatigue)

  • Cognitive Function Trial (Resnick et al., JAMA)2017

    No benefit for delayed verbal memory or other cognitive measures in men with age-associated memory impairment

  • Bone Trial (Snyder et al., JAMA Internal Medicine)2017

    Increased spine and hip volumetric BMD and estimated bone strength

  • Anemia Trial (Roy et al., JAMA Internal Medicine)2017

    More men corrected anemia with testosterone than placebo

  • Cardiovascular Trial (Budoff et al., JAMA)2017

    Testosterone INCREASED non-calcified coronary artery plaque volume on CT angiography vs placebo - an adverse imaging signal