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Tst5.6

Testosterone (TRT) Research

Mostly mechanism / observational

658 peer-reviewed studies

What the evidence says

Mostly mechanism / observational

Most Testosterone (TRT) studies are mechanism or observational rather than RCTs that measure a clinical effect — keep findings provisional.

Most evidence is from high-quality meta-analyses and randomised trials published 1968–2026 with a typical study size of 55,593 participants.

Based on 658 studies · 95 meta-analyses · 521 RCTs · 55,593 total participants

Confidence

High confidence

By outcome

Sexual function & men's vitalityIn the Testosterone Trials, one year of TRT in older hypogonadal men improved sexual activity, desire, and erectile function — the most consistent symptomatic benefit in diagnosed deficiency · Weeks to months · Corrects diagnosed low testosterone (replacement to physiologic levels); benefits are indication-specific to hypogonadism, not an anti-aging result · Weeks to months
Mostly mechanism / observational610 studies
Body composition & muscleRCT meta-analyses show TRT increases lean mass, reduces fat mass and modestly increases muscle strength in hypogonadal men · Months
Mostly mechanism / observational35 studies
Safety profile
Mostly mechanism / observational29 studies
Heart & blood pressure
Mostly mechanism / observational27 studies
Fertility & spermatogenesis
Mostly mechanism / observational26 studies
Bone healthTRT raises bone mineral density and estimated bone strength in hypogonadal men · Months
Mostly mechanism / observational19 studies
Depression & mood
Mostly mechanism / observational16 studies
Anemia & hematology
Mostly mechanism / observational4 studies

Steady research

108 studies in the last 5 years · Latest meta-analysis: 2026

196819972026

1Meta-Analysis2026

Phuyal D, Yacoub S, Belardo ZE, Rampazzo A, Bassiri Gharb B · Aesthetic Plast Surg (2026)

Testosterone (TRT) Research

Mostly mechanism / observational

The Impact of Testosterone Supplementation on Surgical Complications in Gender-Affirming Mastectomy: A Meta-Analysis.

Effect of testosterone replacement therapy on fracture risk in hypogonadal men: A systematic review and meta-analysis of randomized controlled trials.

Effects of gender affirming hormone therapy with testosterone on renal function of assigned female at birth transgender people: a meta-analysis.

Long-Term Cardiovascular Safety of Testosterone-Replacement Therapy in Middle-Aged and Older Men: A Meta-analysis of Randomized Controlled Trials.

The Effects of Testosterone Replacement Therapy in Adult Men With Metabolic Dysfunction-Associated Steatotic Liver Disease: A Systematic Review and Meta-analysis.

Biochemical liver damage during gender affirming therapy in trans adults assigned female at birth: a meta-analysis.

The effects and safety of testosterone replacement therapy for men with hypogonadism: the TestES evidence synthesis and economic evaluation.

Effects of Testosterone Replacement Therapy on Metabolic Syndrome in Male Patients-Systematic Review.

Short-Term Changes in Bone Metabolism Among Transgender Men Starting Gender-Affirming Hormone Therapy: A Systematic Review and Meta-analysis.

Testosterone replacement therapy and vascular thromboembolic events: a systematic review and meta-analysis.

Cardiovascular Outcomes of Hypogonadal Men Receiving Testosterone Replacement Therapy: A Meta-analysis of Randomized Controlled Trials.

Association between testosterone replacement therapy and cardiovascular outcomes: A meta-analysis of 30 randomized controlled trials.

Effect of testosterone replacement therapy on lower urinary tract symptoms: A systematic review and network meta-analysis.

Cardiovascular safety of testosterone replacement therapy in men: an updated systematic review and meta-analysis.

Testosterone use for hypoactive sexual desire disorder in postmenopausal women.

Safety and Efficacy of Testosterone Therapy on Musculoskeletal Health and Clinical Outcomes in Men: A Systematic Review and Meta-Analysis of Randomized Placebo-Controlled Trials.

Effects of Testosterone Replacement Therapy on Muscle Strength in Older Men with Low to Low-Normal Testosterone Levels: A Systematic Review and Meta-Analysis.

Higher live birth rate following transdermal testosterone pretreatment in poor responders: a systematic review and meta-analysis.

Cardiovascular Morbidity and Mortality in Men - Findings From a Meta-analysis on the Time-related Measure of Risk of Exogenous Testosterone.

The Effect of Route of Testosterone on Changes in Hematocrit: A Systematic Review and Bayesian Network Meta-Analysis of Randomized Trials.