Testosterone Replacement Therapy for Healthy Aging in Older Men: Is Maintaining Young-Adult Testosterone Levels Safe and Evidence-Based?
A Narrative Review of Current Evidence and United States and European Guidelines
By Ori Scott, M.Sc. Nutrition
Registered Dietitian (Israel)
Founder, Healthy Habits Coaching
Abstract
Background
Serum testosterone concentrations, and particularly free testosterone concentrations, tend to decline with advancing age in men. This physiological observation has generated increasing interest in testosterone replacement therapy (TRT) not only for established male hypogonadism but also as a potential strategy to preserve physical, sexual, metabolic, and cognitive characteristics associated with younger adulthood. These applications are fundamentally different. Testosterone replacement for symptomatic men with consistently low testosterone concentrations is an established medical intervention, whereas pharmacologically maintaining testosterone concentrations characteristic of younger men in otherwise healthy older adults represents a proposed preventive or anti-aging intervention.
Objective
This narrative review evaluates whether contemporary evidence supports testosterone therapy as an anti-aging intervention in men, with particular emphasis on men aged ≥65 years, and whether such treatment can reasonably be approached using protocols established for confirmed male hypogonadism. The review examines age-related total and free testosterone reference data; indications for testosterone testing; United States and European diagnostic criteria; therapeutic targets; cardiovascular, hematologic, prostate, skeletal, metabolic, sexual, reproductive, cognitive, and functional outcomes; regulatory developments; and current monitoring recommendations.
Methods
A focused narrative review was undertaken using major clinical-practice guidelines, professional consensus statements, regulatory documents, randomized controlled trials, prespecified analyses of major trials, and relevant systematic reviews and meta-analyses. Particular emphasis was placed on evidence published from 2021 through September 2026, while earlier landmark studies were retained when they remain fundamental to contemporary reference intervals, diagnostic criteria, or treatment recommendations. Priority was given to guidance and evidence from the Endocrine Society, European Association of Urology (EAU), European Academy of Andrology (EAA), European Male Ageing Study (EMAS) expert group, American Urological Association (AUA), U.S. Food and Drug Administration (FDA), European Medicines Agency (EMA), and the Testosterone Replacement Therapy for Assessment of Long-term Vascular Events and Efficacy Response in Hypogonadal Men (TRAVERSE) program.
Results
Contemporary U.S. and European professional guidance consistently distinguishes a low biochemical testosterone concentration from the clinical diagnosis of hypogonadism. Diagnosis requires compatible symptoms or signs together with repeatedly low morning testosterone concentrations measured using reliable assays, followed by evaluation of the underlying cause. Routine population screening of asymptomatic men across the lifespan is not currently recommended. Testing is appropriate when symptoms or signs suggest androgen deficiency and should be considered in selected conditions associated with an increased prevalence of testosterone deficiency.
The AUA uses total testosterone <300 ng/dL (<10.4 nmol/L) as a reasonable diagnostic cutoff, whereas the EAU uses <346 ng/dL (<12 nmol/L) in symptomatic men. The Endocrine Society emphasizes symptoms or signs together with unequivocally and consistently low testosterone concentrations rather than diagnosis from a single laboratory result.
The harmonized total-testosterone reference interval in healthy, nonobese men aged 19–39 years is approximately 264–916 ng/dL (9.2–31.8 nmol/L). Free testosterone shows a more pronounced age-associated decline. However, population reference distributions are descriptive and should not be interpreted as therapeutic targets.
TRAVERSE substantially strengthened evidence regarding medium-term cardiovascular safety in appropriately selected men with hypogonadism. Major adverse cardiovascular events occurred in 7.0% of testosterone-treated participants and 7.3% receiving placebo. Nevertheless, signals involving pulmonary embolism, atrial fibrillation, and acute kidney injury require consideration, and long-term safety extending over decades remains unestablished. Contemporary randomized evidence has not demonstrated a major increase in prostate events over the periods studied. TRT can improve sexual symptoms in appropriately selected hypogonadal men, correct testosterone-deficiency-associated anemia, increase lean mass, reduce fat mass, and increase bone-density measures. Evidence has not established prevention of frailty, dementia, cardiovascular disease, type 2 diabetes, fractures, or mortality. Recent randomized evidence does not support TRT for fracture prevention and has raised concern regarding increased clinical fracture incidence.
Conclusions
Current evidence supports TRT for appropriately selected men with symptomatic, biochemically confirmed hypogonadism, including selected men aged >65 years. Current evidence does not establish TRT as a safe and effective anti-aging intervention for maintaining otherwise healthy older men at testosterone concentrations characteristic of young adulthood. Physiological replacement of demonstrated deficiency and pharmacological prevention of normal age-associated testosterone decline therefore cannot presently be regarded as equivalent clinical practices. No major U.S. or European professional endocrinology or urology guideline reviewed for this article recommends routine testosterone screening throughout adult life for the purpose of detecting age-related decline or testosterone administration solely to maintain young-adult concentrations during normal aging.
Keywords: testosterone; testosterone replacement therapy; TRT; male hypogonadism; late-onset hypogonadism; aging men; healthy aging; anti-aging; testosterone screening; testosterone reference range; TRAVERSE.
1. Introduction
Testosterone concentrations change throughout the male lifespan. Although this observation is well established, its biological and clinical interpretation is considerably more complex than the frequently used concept of a progressive “testosterone deficiency of aging.”
Aging is accompanied by changes in testicular function, hypothalamic-pituitary regulation, sex hormone-binding globulin (SHBG), body composition, insulin sensitivity, chronic disease burden, medication exposure, sleep, physical activity, and general health. Consequently, a testosterone concentration lower than that observed earlier in an individual's life does not by itself demonstrate pathological androgen deficiency.
This distinction has acquired increasing clinical importance because testosterone is now discussed in two substantially different contexts.
The first is testosterone replacement therapy for male hypogonadism. In this setting, a man has clinical manifestations compatible with androgen deficiency together with repeatedly and reliably demonstrated low testosterone concentrations. The objective of treatment is restoration of physiological androgen exposure and improvement of clinically relevant manifestations.
The second is testosterone as an anti-aging or preventive intervention. Under this model, testosterone would be administered to an otherwise healthy aging man whose endogenous testosterone may remain physiologically adequate but has declined relative to concentrations present during younger adulthood. The objective would be to preserve a younger hormonal phenotype in an attempt to prevent or attenuate age-associated deterioration.
These concepts should not be conflated.
The clinically relevant question is therefore not simply whether testosterone declines with age. Rather, it is whether pharmacologically preventing or reversing that decline improves clinically meaningful outcomes sufficiently to justify the immediate and cumulative risks of long-term treatment.
A related question is whether testosterone should be measured routinely throughout adult male life so that individual age-associated decline can be detected before symptoms appear. If preservation of young-adult testosterone were an established preventive intervention, routine longitudinal surveillance might be logically attractive. Current professional guidance, however, does not establish such a screening strategy.
The present review therefore addresses four related questions:
What testosterone concentrations are observed in healthy young, middle-aged, and older men?
When should testosterone be measured, and should asymptomatic men undergo routine age-based screening?
How do U.S. and European professional organizations diagnose and treat established testosterone deficiency?
Does current evidence justify extending those treatment principles to otherwise healthy older men for the purpose of maintaining young-adult testosterone concentrations?
2. Methods
This article was designed as a focused narrative review rather than a systematic review or formal meta-analysis.
Priority was given to clinical-practice guidelines and consensus statements from major professional organizations, regulatory assessments, large randomized controlled trials, prespecified secondary analyses of those trials, and systematic reviews and meta-analyses relevant to clinically important outcomes.
The principal professional and regulatory sources included the Endocrine Society, AUA, EAU, EAA, EMAS expert group, FDA, and EMA. Particular emphasis was placed on the TRAVERSE program because it represents the largest randomized cardiovascular-safety investigation of testosterone therapy performed to date.
The principal period of interest was 2021 through September 2026. Earlier studies were included when required to establish young-adult testosterone reference intervals, diagnostic principles, or evidence underlying current clinical recommendations.
Evidence concerning classical organic hypogonadism, functional or late-onset hypogonadism, and men without established hypogonadism was distinguished whenever possible. This distinction is essential because efficacy or safety demonstrated during physiological replacement of a documented deficiency cannot automatically be extrapolated to long-term hormonal intervention in eugonadal individuals.
Regulatory decisions were considered separately from recommendations issued by professional medical organizations. Changes in drug labeling were not interpreted as equivalent to professional endorsement of preventive or anti-aging use.
3. Testosterone Across the Male Lifespan: What Is “Normal”?
3.1 The meaning of a normal testosterone concentration
The term normal testosterone is frequently used without defining what normality means.
At least three distinct concepts must be separated:
a population reference interval;
a diagnostic threshold used together with clinical findings to identify hypogonadism; and
a therapeutic target during treatment of established hypogonadism.
These values are related but are not interchangeable.
A major harmonization study involving 9,054 community-dwelling men from U.S. and European cohorts standardized testosterone measurements against a reference method. Among healthy, nonobese men aged 19–39 years, the harmonized total-testosterone reference interval was approximately 264–916 ng/dL (9.2–31.8 nmol/L), with a median of approximately 531 ng/dL (18.4 nmol/L).
Approximate age-stratified distributions from the harmonized cohorts illustrate the considerable overlap between age groups.
Age | Median total testosterone | Approximate reference distribution |
19–39 years | 531 ng/dL (18.4 nmol/L) | 267–929 ng/dL (9.3–32.2 nmol/L) |
40–49 years | 481 ng/dL (16.7 nmol/L) | 235–929 ng/dL (8.2–32.2 nmol/L) |
50–59 years | 477 ng/dL (16.5 nmol/L) | 219–929 ng/dL (7.6–32.2 nmol/L) |
60–69 years | 477 ng/dL (16.5 nmol/L) | 218–929 ng/dL (7.6–32.2 nmol/L) |
70–79 years | 477 ng/dL (16.5 nmol/L) | 218–926 ng/dL (7.6–32.1 nmol/L) |
80–99 years | 476 ng/dL (16.5 nmol/L) | 157–913 ng/dL (5.4–31.7 nmol/L) |
These values describe populations. They do not define treatment targets for individual older men.
Total testosterone also does not completely characterize androgen exposure. SHBG changes with age and with numerous metabolic and medical conditions, potentially producing substantial differences between total and biologically available testosterone.
3.2 Free testosterone and aging
Age-associated decline becomes more apparent when free testosterone is examined.
Recent reference data obtained using equilibrium dialysis followed by mass spectrometry reported progressively lower median free-testosterone concentrations with advancing age.
Age | Median free testosterone | Approximate reference interval |
18–29 years | 11.7 ng/dL (406 pmol/L) | 6.9–25.3 ng/dL (239–877 pmol/L) |
30–39 years | 9.8 ng/dL (340 pmol/L) | 5.0–18.8 ng/dL (173–652 pmol/L) |
40–49 years | 8.1 ng/dL (281 pmol/L) | 4.2–14.4 ng/dL (147–499 pmol/L) |
50–59 years | 7.1 ng/dL (246 pmol/L) | 4.2–12.8 ng/dL (147–444 pmol/L) |
60–69 years | 6.3 ng/dL (218 pmol/L) | 3.0–11.6 ng/dL (104–402 pmol/L) |
70–79 years | 5.4 ng/dL (187 pmol/L) | 2.2–8.9 ng/dL (76–309 pmol/L) |
≥80 years | 4.3 ng/dL (149 pmol/L) | 1.4–7.2 ng/dL (49–250 pmol/L) |
These observations provide evidence that androgen exposure changes substantially across adulthood, particularly when free testosterone is considered.
They do not establish that the physiological concentration of a 70- or 80-year-old man should pharmacologically be returned to the median concentration of a 20- or 30-year-old man.
Nor do they establish that an individual's testosterone concentration should be maintained at the level measured earlier in his own adulthood.
The difference between a reference value and a therapeutic target is therefore fundamental to evaluation of anti-aging TRT.
4. Should Testosterone Be Routinely Tested Throughout Adult Male Life?
An important distinction must be made between population screening for testosterone deficiency and diagnostic testosterone testing when hypogonadism is clinically suspected.
Current professional guidance does not support routine measurement of serum testosterone at predetermined ages in otherwise healthy, asymptomatic men.
There is no established recommendation that testosterone should automatically be incorporated into routine laboratory screening at ages 30, 40, 50, 60, or 65 years simply to document age-associated hormonal decline.
The Endocrine Society recommends against routine screening of men in the general population for hypogonadism. Its contemporary position continues to find insufficient evidence to recommend population-level testosterone screening of asymptomatic men.
European guidance similarly favors evaluation when clinical manifestations suggest late-onset hypogonadism rather than indiscriminate screening of the general male population.
This approach differs conceptually from screening for conditions such as hypertension or dyslipidemia. For those disorders, identification of an abnormality in an asymptomatic individual can trigger interventions supported by evidence of reduced cardiovascular morbidity or mortality.
No comparable evidence currently demonstrates that identifying declining testosterone in an asymptomatic man and pharmacologically maintaining a young-adult concentration prevents major age-related morbidity or mortality.
Therefore, the present evidence does not establish testosterone as a routine longitudinal “aging biomarker” that should be measured throughout every man's adult life for the purpose of deciding when replacement should begin.
5. When Should Testosterone Be Measured?
Serum testosterone should be measured when there is a clinical reason to suspect androgen deficiency rather than solely because a man has reached a particular chronological age.
Testing is particularly appropriate when clinical manifestations compatible with hypogonadism are present. These may include reduced sexual desire, reduced spontaneous or morning erections, erectile dysfunction in an appropriate clinical context, infertility, regression or loss of secondary sexual characteristics, reduced testicular volume, gynecomastia, otherwise unexplained anemia, reduced bone density or osteoporosis, or clinical evidence suggesting hypothalamic, pituitary, or testicular disease.
Certain medical conditions justify a lower threshold for biochemical evaluation even when classical sexual symptoms are absent.
The AUA recommends consideration of testosterone measurement in men with conditions including unexplained anemia, bone-density loss, diabetes mellitus, previous chemotherapy or testicular irradiation, HIV/AIDS, chronic opioid exposure, male infertility, pituitary dysfunction, chronic corticosteroid exposure, and obesity.
This distinction is important:
testosterone is not measured only after hypogonadism has already been confirmed. Testosterone measurement is part of the process by which suspected hypogonadism is confirmed or excluded.
What is not currently recommended is indiscriminate testing of every asymptomatic man solely to identify the normal decline associated with aging.
6. Obesity, Metabolic Disease, and Interpretation of Low Testosterone
Obesity deserves particular attention because it is strongly associated with reduced testosterone concentrations.
Increased adiposity can reduce SHBG and thereby lower measured total testosterone. Obesity can also produce functional suppression of the hypothalamic-pituitary-testicular axis. Consequently, a low total testosterone concentration in a man with obesity does not automatically establish irreversible testicular or hypothalamic-pituitary disease.
Obesity, insulin resistance, type 2 diabetes, obstructive sleep apnea, systemic illness, medications, energy restriction, and other potentially reversible factors should therefore be considered when interpreting testosterone results.
Where functional suppression is suspected, management of contributing conditions and reassessment of testosterone may be appropriate before concluding that lifelong replacement is required.
This distinction also illustrates why screening based on a single testosterone concentration can be misleading. The laboratory result must be interpreted within the individual's broader physiological and clinical context.
7. How Testosterone Should Be Tested
7.1 Initial biochemical evaluation
When testosterone testing is clinically indicated, serum total testosterone is generally the first-line biochemical investigation.
The sample should ordinarily be obtained:
during the early morning, generally approximately 07:00–10:00;
preferably while fasting;
when the patient is clinically stable rather than during an acute systemic illness; and
using a reliable and appropriately standardized assay.
A single low testosterone measurement is insufficient to establish the diagnosis.
If the initial concentration is below the relevant diagnostic threshold, total testosterone should ordinarily be repeated on a separate morning under appropriate conditions.
The AUA uses <300 ng/dL (<10.4 nmol/L) as a reasonable biochemical threshold supporting testosterone deficiency.
The EAU uses <346 ng/dL (<12 nmol/L) as a reliable threshold for late-onset hypogonadism in a symptomatic man and recommends confirmation on at least two separate occasions.
The Endocrine Society requires unequivocally and consistently low testosterone concentrations together with compatible clinical manifestations rather than diagnosis from a single laboratory result.
Thus, an isolated testosterone concentration of, for example, 270 ng/dL (9.4 nmol/L) should initiate confirmation and clinical evaluation rather than automatically initiate TRT.
7.2 Free testosterone and SHBG
Free testosterone should not necessarily replace total testosterone as the universal initial screening test.
Assessment of SHBG and free testosterone becomes particularly useful when total testosterone is borderline or when a condition likely to alter SHBG makes total testosterone difficult to interpret.
Examples include obesity, aging, substantial changes in body composition, and selected endocrine, hepatic, and medication-related conditions.
When free testosterone requires direct measurement, equilibrium dialysis represents a reference method. Alternatively, free testosterone may be calculated from total testosterone, SHBG, and albumin using an appropriately validated equation.
Methods with poor analytical reliability should not be used to establish a diagnosis requiring long-term treatment.
8. Evaluation After Low Testosterone Is Confirmed
Once repeatedly low testosterone has been demonstrated in an appropriate clinical context, evaluation should progress from detection of the abnormality to determination of its cause.
Serum luteinizing hormone (LH) and follicle-stimulating hormone (FSH) assist in distinguishing primary testicular hypogonadism from secondary hypothalamic-pituitary hypogonadism.
Low testosterone accompanied by elevated gonadotropins supports primary testicular dysfunction.
Low testosterone accompanied by low or inappropriately normal LH and FSH suggests secondary hypogonadism.
Prolactin should be measured when secondary hypogonadism is suspected, particularly when low or normal LH accompanies low testosterone or when clinical features suggest hyperprolactinemia.
Selected patients with severe secondary hypogonadism, persistent hyperprolactinemia, additional pituitary hormonal abnormalities, or symptoms suggesting a pituitary mass require pituitary imaging and specialist endocrine assessment.
The diagnostic sequence can therefore be summarized as:
clinical indication for testing → morning total testosterone → repeat morning total testosterone if low → confirmation of compatible clinical manifestations → SHBG/free testosterone when indicated → LH/FSH ± prolactin and additional etiological investigation → diagnosis → consideration of treatment.
This sequence differs fundamentally from:
routine annual testosterone measurement → age-associated decline identified → testosterone prescribed to restore young-adult concentrations.
The latter strategy is not currently supported by major U.S. or European professional guidelines.
9. Professional Definitions of Testosterone Deficiency
Despite differences in numerical thresholds, contemporary U.S. and European professional organizations show substantial agreement regarding the clinical diagnosis of hypogonadism.
The Endocrine Society requires clinical manifestations compatible with androgen deficiency together with consistently low, accurately measured testosterone concentrations.
The AUA considers total testosterone <300 ng/dL (<10.4 nmol/L) a reasonable biochemical cutoff supporting diagnosis. Two separate early-morning measurements are required, and biochemical low testosterone alone is insufficient without compatible symptoms or signs.
The EAU uses total testosterone <346 ng/dL (<12 nmol/L) as a reliable threshold for late-onset hypogonadism when compatible symptoms are present. Measurements should be obtained under standardized conditions and repeated before treatment.
Thus, although individual numerical thresholds differ somewhat, the conceptual consensus is strong:
hypogonadism is a clinical and biochemical diagnosis, not a laboratory number and not a consequence of chronological age alone.
10. Testosterone Therapy in Men Older Than 65 Years
Age ≥65 years is not, by itself, a contraindication to TRT.
Neither is age-associated testosterone decline an automatic indication for treatment.
The Endocrine Society recommends against routinely prescribing testosterone to all men aged ≥65 years merely because testosterone concentrations are low.
Treatment can be considered individually when an older man has compatible symptoms or conditions together with consistently and unequivocally low morning testosterone concentrations and after the potential benefits, uncertainties, and risks have been discussed.
The EMAS position statement similarly supports consideration of TRT in symptomatic older men with confirmed low testosterone rather than routine treatment of chronological aging.
The specialist consensus therefore supports neither of two extreme interpretations: testosterone should not automatically be withheld because a man is older than 65, but it should not routinely be prescribed because aging has produced a lower testosterone concentration.
11. Therapeutic Targets in Established Hypogonadism
Once genuine hypogonadism has been established, professional guidelines seek physiological normalization rather than maximization of testosterone concentrations.
The Endocrine Society generally recommends targeting testosterone within the mid-normal physiological range.
The AUA describes a practical therapeutic target of approximately 450–600 ng/dL (15.6–20.8 nmol/L) using the minimum dose necessary to achieve an appropriate physiological response.
European guidance similarly seeks normalization rather than supraphysiological exposure.
These recommendations concern men in whom testosterone treatment is clinically indicated.
They do not imply that a healthy 70-year-old man with an endogenous total testosterone concentration of 450 ng/dL (15.6 nmol/L) should receive testosterone to raise his concentration toward the median or upper-normal value observed in young adults.
Nor do they establish that a man should be returned to his own testosterone concentration measured at age 25 or 35.
No major professional guideline establishes such an objective.
12. Cardiovascular Safety: What TRAVERSE Changed
Cardiovascular safety represented one of the major unresolved questions in testosterone medicine before TRAVERSE.
TRAVERSE enrolled 5,204 men aged 45–80 years who had symptoms consistent with hypogonadism, two testosterone concentrations below 300 ng/dL (10.4 nmol/L), and established cardiovascular disease or increased cardiovascular risk.
Participants were randomized to transdermal testosterone or placebo.
Major adverse cardiovascular events occurred in 7.0% of testosterone-treated men and 7.3% receiving placebo. Testosterone satisfied the prespecified criterion for cardiovascular noninferiority.
This finding materially changed the cardiovascular evidence surrounding legitimate TRT.
It provides substantial reassurance that physiological testosterone replacement in appropriately selected men with hypogonadism does not produce a major short- to medium-term increase in the composite risk of cardiovascular death, nonfatal myocardial infarction, or nonfatal stroke.
The result nevertheless requires careful interpretation.
TRAVERSE evaluated men with symptoms and repeatedly low testosterone. It did not evaluate decades of testosterone exposure in healthy eugonadal men beginning treatment for prevention of aging.
Furthermore, pulmonary embolism, atrial fibrillation, and acute kidney injury occurred more frequently in testosterone-treated participants.
The appropriate interpretation is therefore that contemporary evidence is reassuring regarding major cardiovascular events during physiological replacement of appropriately selected hypogonadal men over the studied period.
It does not establish lifetime cardiovascular safety of preventive testosterone administration.
13. Hematologic Effects and Blood Pressure
Erythrocytosis is among the most consistent adverse effects of testosterone therapy.
Current European and U.S. guidance therefore requires hematologic surveillance.
The EAU identifies elevated hematocrit as the most common adverse effect of TRT. Hematocrit should be assessed before treatment and during follow-up.
A hematocrit exceeding 54% requires intervention. Depending on clinical circumstances, management may involve dose reduction, temporary withdrawal, change of formulation, and/or venesection.
Patients at increased risk of secondary erythrocytosis require closer surveillance.
Blood pressure is also relevant. Following reassessment of cardiovascular evidence and ambulatory blood-pressure data, the FDA incorporated class-wide information regarding testosterone-associated increases in blood pressure.
These adverse effects can generally be monitored when a patient has an established therapeutic indication.
Their risk-benefit significance becomes different when testosterone is proposed for preventive enhancement in an otherwise healthy individual for whom long-term clinical benefit has not been demonstrated.
14. Prostate Safety
Concern that testosterone replacement inevitably stimulates clinically important prostate cancer has not been confirmed by contemporary randomized evidence.
The TRAVERSE prostate-safety analysis found low incidences of high-grade prostate cancer, prostate cancer overall, acute urinary retention, and invasive prostate procedures, without statistically significant differences between treatment groups during the trial period.
Current European guidance consequently considers available evidence reassuring regarding prostate cancer during physiological testosterone replacement while emphasizing the absence of sufficiently long prospective follow-up to establish lifetime safety.
The appropriate conclusion is therefore neither that testosterone causes prostate cancer nor that lifetime prostate safety has been proved.
Rather:
medium-term randomized evidence is reassuring, while long-term risk remains incompletely established.
This limitation is particularly relevant to anti-aging therapy because prostate carcinogenesis may evolve over considerably longer periods than contemporary randomized testosterone trials.
15. Sexual Function
Sexual manifestations—particularly reduced sexual desire, fewer spontaneous erections, and erectile difficulties—are among the symptoms most closely associated with clinically important androgen deficiency.
TRT can improve sexual desire and several measures of sexual activity in appropriately selected hypogonadal men. Benefits tend to be greater when baseline testosterone is clearly low.
Evidence across elderly populations nevertheless remains heterogeneous, and testosterone should not be regarded as a universal treatment for erectile dysfunction.
The clinically relevant distinction remains baseline androgen status.
Evidence supporting testosterone for sexual manifestations in men with genuine biochemical hypogonadism is substantially stronger than evidence supporting testosterone as a sexual-performance enhancer in eugonadal older men.
16. Muscle Mass, Body Composition, and Physical Function
Testosterone has well-established anabolic effects.
Physiological replacement in hypogonadal men generally increases lean body mass and can reduce fat mass. These effects provide a biologically plausible basis for interest in testosterone as an intervention against sarcopenia and frailty.
Changes in body composition, however, should not automatically be equated with clinically meaningful improvements in physical function.
Increases in lean mass have generally been more consistent than improvements in strength, mobility, disability, falls, or frailty.
Existing evidence therefore does not establish that long-term testosterone administration fundamentally alters the trajectory of physical aging in otherwise healthy men.
This distinction is important when evaluating anti-aging claims.
A treatment can modify a biological characteristic associated with youth without demonstrating that it prevents disability or extends healthy lifespan.
17. Bone Density and Fracture Risk
Testosterone therapy can increase bone mineral density and estimated bone strength in hypogonadal men.
This previously generated a biologically plausible expectation that TRT might reduce fracture incidence.
Randomized clinical evidence has not confirmed that expectation.
The TRAVERSE fracture analysis found no reduction in clinical fractures. Instead, clinical fractures occurred more frequently among testosterone-treated participants.
This finding demonstrates an important principle relevant to anti-aging medicine:
improvement in a surrogate endpoint such as bone density cannot automatically be interpreted as improvement in the clinical outcome that matters most—fracture prevention.
TRT should therefore not presently be regarded as an established fracture-prevention treatment.
18. Anemia
Correction of anemia represents one of the clearer nonsexual benefits demonstrated in testosterone-deficient men.
The TRAVERSE anemia substudy found that testosterone corrected anemia in a greater proportion of hypogonadal men who were anemic at baseline and reduced development of anemia among participants without anemia at baseline.
This provides evidence for a clinically meaningful effect of replacement in appropriately selected testosterone-deficient men.
It does not provide a rationale for increasing testosterone in nonanemic, eugonadal older adults.
19. Metabolic Health and Type 2 Diabetes
Low testosterone frequently accompanies obesity, insulin resistance, metabolic syndrome, and type 2 diabetes.
The relationship is complex and bidirectional. Association does not establish that testosterone replacement treats the underlying metabolic disorder.
The TRAVERSE diabetes substudy did not demonstrate that TRT prevented progression from prediabetes to diabetes or produced a clinically established preventive effect on glycemic deterioration.
Accordingly, testosterone should not be regarded as an established treatment for prevention of type 2 diabetes.
When obesity-associated functional suppression is present, management of obesity and related metabolic disease remains clinically important irrespective of whether testosterone treatment is ultimately considered.
20. Cognition, Vitality, and Longevity
One of the strongest theoretical arguments for anti-aging testosterone is the possibility that restoration of youthful hormonal concentrations might preserve cognition, vitality, or longevity.
At present, convincing clinical evidence for these outcomes is lacking.
Studies examining mood, vitality, and cognition have produced inconsistent results, and no adequately powered long-duration randomized trial has demonstrated that testosterone prevents dementia.
More importantly, no randomized trial has demonstrated that maintaining young-adult testosterone concentrations in otherwise healthy older men extends life.
For testosterone to qualify as an evidence-based anti-aging intervention rather than replacement therapy, clinically meaningful evidence would ideally demonstrate reductions in outcomes such as frailty, disability, dementia, cardiovascular disease, fractures, loss of independence, or mortality.
Such evidence has not presently been established.
21. Fertility and the Hypothalamic-Pituitary-Testicular Axis
Exogenous testosterone should not be conceptualized as simply adding testosterone to otherwise unchanged physiology.
Exogenous testosterone suppresses hypothalamic-pituitary gonadotropin signaling, reduces intratesticular testosterone production, and suppresses spermatogenesis.
Professional guidelines therefore advise against exogenous testosterone in men actively seeking fertility.
This physiology has additional conceptual relevance to anti-aging treatment.
Pharmacologically maintaining the serum testosterone concentration of a younger man does not recreate the younger man's endocrine physiology because endogenous hypothalamic-pituitary-testicular regulation has been altered.
A youthful serum testosterone concentration is therefore not synonymous with a youthful reproductive endocrine state.
22. U.S. and European Regulatory Positions
The regulatory assessment of testosterone changed substantially following TRAVERSE.
The FDA concluded that TRAVERSE did not demonstrate a clinically important increase in major adverse cardiovascular outcomes, contributing to subsequent changes in testosterone product labeling. Blood-pressure effects have simultaneously received greater regulatory attention.
Further labeling revisions occurred in 2026.
These developments should be interpreted carefully.
Changes in FDA labeling are not equivalent to professional endorsement of testosterone as an anti-aging intervention.
Current FDA information continues to distinguish approved testosterone treatment for medically recognized hypogonadal conditions from use of testosterone simply to raise concentrations in men without an established medical indication.
European regulatory and professional frameworks similarly recognize testosterone primarily as replacement treatment for established hypogonadism rather than as a pharmacological intervention to maintain young-adult hormonal concentrations in healthy aging men.
Regulatory evolution following TRAVERSE therefore strengthens the evidence concerning safety of appropriate replacement more than it establishes a new preventive indication.
23. Established Clinical Protocol for Testosterone Replacement Therapy
Current U.S. and European recommendations converge on a broadly similar clinical pathway.
Before treatment, the clinician should establish compatible symptoms or signs and obtain at least two appropriately timed morning testosterone measurements.
When total testosterone is borderline or potentially misleading because of altered SHBG, SHBG and appropriately measured or calculated free testosterone can provide additional diagnostic information.
LH and FSH are used to distinguish primary from secondary hypogonadism. Prolactin, pituitary imaging, or additional endocrine testing may be required when clinically indicated.
Potentially reversible contributors should be sought before assuming a permanent requirement for replacement.
Fertility intentions should be established before exogenous testosterone is prescribed.
Baseline evaluation generally includes hematocrit and cardiovascular assessment, with prostate assessment and PSA testing according to age, individual risk, guideline recommendations, and shared clinical decision-making.
Treatment is titrated toward physiological rather than supraphysiological testosterone concentrations.
Clinical response matters as much as the laboratory concentration. Normalization of testosterone without meaningful improvement in the manifestations for which treatment was initiated should prompt reassessment of the diagnosis and the rationale for continued treatment.
Monitoring generally includes testosterone concentration, hematocrit, clinical response, adverse effects, blood pressure, and appropriate prostate surveillance.
European guidance recommends testosterone and hematocrit assessment approximately 3, 6, and 12 months after initiation and annually thereafter, with more frequent evaluation when clinically indicated.
A hematocrit >54% requires intervention.
24. Routine Screening, Diagnostic Testing, and Treatment: Practical Distinction
The contemporary evidence can be summarized as follows:
Clinical situation | Current evidence-based approach |
Healthy, asymptomatic man undergoing routine preventive examination | Routine population testosterone screening is not recommended |
Healthy asymptomatic man reaches age 40, 50, 60, or 65 years | Age alone does not establish an indication for testosterone testing |
Man with symptoms or signs compatible with testosterone deficiency | Testosterone testing is appropriate |
Man with selected conditions associated with increased prevalence of testosterone deficiency | Testing should be considered according to clinical context and guideline recommendations |
Man with obesity and possible functional hypogonadism | Testosterone may be evaluated, but low values require careful interpretation and assessment of potentially reversible causes |
One unexpectedly low testosterone measurement | Repeat appropriately timed morning measurement before establishing biochemical deficiency |
Repeatedly low testosterone plus compatible clinical manifestations | Etiological evaluation is required before deciding on treatment |
Confirmed hypogonadism treated with TRT | Scheduled biochemical and clinical safety monitoring is required |
Eugonadal older man wishing to maintain the testosterone level of young adulthood | Not an established guideline-supported anti-aging indication |
This distinction prevents an important misunderstanding.
Testosterone measurement is not reserved until after hypogonadism has somehow already been diagnosed. It is part of the diagnostic process.
What professional guidance does not currently endorse is routine testing of every asymptomatic man in order to identify the moment at which his testosterone begins to decline from his individual young-adult baseline.
25. Can an Individual Young-Adult Testosterone Baseline Guide Treatment Later in Life?
An intuitively attractive preventive strategy would be to measure testosterone in healthy men during young or middle adulthood, establish each individual's baseline, and subsequently initiate TRT when concentrations decline substantially from that baseline.
Current guidelines do not establish this approach.
A man whose testosterone decreases from 700 ng/dL (24.3 nmol/L) at age 30 to 450 ng/dL (15.6 nmol/L) at age 70 has experienced a substantial relative decline. Nevertheless, if he remains asymptomatic and his current testosterone remains physiologically adequate, current evidence does not establish that returning him pharmacologically to 700 ng/dL (24.3 nmol/L) improves health outcomes.
Conversely, an older man with symptoms and repeatedly low testosterone should be evaluated even if no young-adult baseline measurement exists.
Thus, contemporary diagnosis is based principally on current clinical manifestations, current repeated biochemical measurements, and etiological evaluation, rather than percentage decline from an individual's historical peak testosterone concentration.
Whether longitudinal personal testosterone trajectories could eventually improve prediction of clinically significant androgen deficiency is a legitimate research question, but it has not yet become an established clinical strategy.
26. Can the Established Hypogonadism Protocol Be Applied to Anti-Aging TRT?
This is the central question of this review.
The available evidence does not establish that it can.
A monitoring protocol can make administration of a medication more controlled. It cannot establish that treatment is beneficial for an indication that has not itself been demonstrated.
Conventional TRT begins with a clinically identified disorder: manifestations consistent with androgen deficiency accompanied by repeatedly low testosterone concentrations.
Treatment attempts to restore deficient androgen exposure toward physiological concentrations.
Preventive or anti-aging testosterone begins from a fundamentally different premise. An older man may have no established hypogonadal disorder and testosterone concentrations that remain physiologically adequate but receive exogenous testosterone because those concentrations are lower than during younger adulthood.
The principal unanswered questions are therefore not simply questions of dose or monitoring.
They are questions of clinical benefit and long-term safety:
Does maintaining young-adult testosterone prevent frailty?
Does it prevent disability?
Does it prevent dementia?
Does it reduce cardiovascular disease?
Does it prevent fractures?
Does it preserve functional independence?
Does it improve health-related quality of life over decades?
Does it extend healthy lifespan?
Does it reduce mortality?
What are the cumulative incidences of erythrocytosis, hypertension, atrial fibrillation, thromboembolic events, and other adverse effects after 10, 20, or 30 years?
What is prostate safety after decades rather than approximately three years?
What are the long-term consequences of continuous pharmacological suppression of the endogenous hypothalamic-pituitary-testicular axis?
Existing randomized evidence cannot adequately answer these questions.
27. Discussion
The evidence surrounding TRT has changed materially during the last five years.
The principal development has been increased confidence regarding the medium-term safety of appropriately prescribed physiological replacement therapy, particularly regarding major cardiovascular events.
That development is clinically important.
It does not establish testosterone as an anti-aging therapy.
TRAVERSE studied men with symptoms and repeatedly low testosterone concentrations. Its findings therefore apply most directly to men resembling the population actually enrolled.
Extrapolating these findings to healthy eugonadal men treated for decades to prevent normal hormonal aging would exceed the evidence.
Similarly, the distinction between biological effects and clinically meaningful anti-aging effects must be preserved.
Testosterone can increase lean mass.
It can increase bone-density measurements.
It can increase hemoglobin.
It can improve certain sexual manifestations in appropriately selected hypogonadal men.
These observations demonstrate androgen biological activity.
They do not demonstrate prevention of biological aging.
The fracture literature provides an instructive example. Improvement in bone-density measures did not translate into demonstrated fracture prevention, and randomized evidence identified a higher incidence of clinical fractures in testosterone-treated men.
The same evidentiary standard should be applied to muscle mass, metabolic health, cognition, vitality, and longevity.
The appropriate endpoint for an anti-aging intervention is not merely restoration of a biomarker associated with youth. It is improvement in clinically meaningful health outcomes.
A further distinction concerns screening.
If maintaining young-adult testosterone concentrations were an established preventive strategy, one might reasonably expect professional organizations to recommend periodic testosterone surveillance beginning before clinically apparent deficiency occurs.
They do not.
Current guidance instead uses a case-finding model: testing is prompted primarily by compatible clinical manifestations or selected conditions associated with an increased likelihood of testosterone deficiency.
The absence of routine screening recommendations does not prove that longitudinal testosterone surveillance could never become useful. It demonstrates that this strategy has not yet met the evidentiary threshold required for routine preventive medicine.
28. Limitations of the Evidence
Several limitations prevent definitive assessment of long-term anti-aging testosterone therapy.
First, the major randomized trials predominantly enrolled men with low testosterone rather than healthy eugonadal men.
Second, follow-up periods are short relative to the decades over which preventive hormone treatment might theoretically be administered.
Third, testosterone formulations, doses, laboratory assays, and target concentrations vary among studies.
Fourth, many outcomes reported in testosterone research are surrogate endpoints rather than major clinical outcomes.
Fifth, older men represent a heterogeneous population with substantial differences in obesity, cardiovascular risk, prostate risk, medication exposure, frailty, SHBG concentrations, and underlying causes of low testosterone.
Sixth, studies demonstrating safety during replacement of deficient testosterone cannot automatically establish safety when treatment is initiated in individuals without deficiency.
Seventh, current age-specific testosterone reference intervals describe population distributions but have not been validated as age-specific thresholds at which treatment should begin.
Eighth, the clinical utility of measuring an individual's testosterone during healthy young adulthood and following the percentage decline longitudinally has not been established.
Finally, absence of demonstrated harm over several years cannot establish absence of harm over several decades.
These limitations should be considered when interpreting both reassuring and concerning findings.
29. Conclusions
The principal question of this review can be answered with reasonable clarity on the basis of contemporary evidence and specialist consensus.
Testosterone replacement therapy is an established treatment for appropriately selected men with clinically significant hypogonadism, including selected men older than 65 years.
Age alone neither establishes the diagnosis nor constitutes an absolute contraindication to treatment.
Diagnosis requires compatible clinical manifestations together with consistently low testosterone concentrations confirmed by appropriately performed laboratory testing and evaluation of the underlying cause.
Routine testosterone screening of all asymptomatic men throughout adult life is not currently recommended by major professional organizations. Age alone—whether 40, 50, 60, or 65 years—is not an established indication for testosterone measurement.
Testing is appropriate when symptoms or signs suggest androgen deficiency and should be considered in selected clinical conditions associated with increased prevalence of testosterone deficiency. Obesity represents an important example but also requires careful interpretation because obesity itself can produce functional and potentially reversible reductions in testosterone.
A single low testosterone result does not establish hypogonadism. Diagnosis generally requires at least two appropriately obtained morning measurements, interpretation within the clinical context, and further etiological evaluation when biochemical deficiency is confirmed.
For men with established hypogonadism, contemporary evidence—particularly TRAVERSE—provides substantially greater reassurance regarding medium-term major cardiovascular and prostate safety than was previously available.
TRT can improve sexual symptoms in appropriately selected hypogonadal men, correct testosterone-deficiency-associated anemia, increase lean mass, reduce fat mass, and increase measures of bone density.
These benefits coexist with recognized adverse effects and unresolved uncertainties. Erythrocytosis and increases in blood pressure require monitoring. Exogenous testosterone suppresses spermatogenesis. Signals involving pulmonary embolism, atrial fibrillation, and acute kidney injury deserve continued attention. Randomized evidence does not support testosterone as a fracture-prevention therapy, and long-term prostate, cardiovascular, and overall safety extending over decades remains incompletely characterized.
Most importantly, available evidence does not establish testosterone therapy as an anti-aging treatment for otherwise healthy eugonadal men.
Young-adult testosterone reference intervals describe population physiology. They are not preventive-treatment targets.
The observation that free testosterone decreases substantially between young adulthood and old age demonstrates an age-associated biological change. It does not establish that reversing that change pharmacologically improves health or longevity.
Likewise, no established guideline currently recommends measuring testosterone routinely during young adulthood to establish a personal hormonal baseline that should subsequently be maintained pharmacologically throughout life.
Consequently, physiological replacement of demonstrated testosterone deficiency and pharmacological maintenance of young-adult testosterone concentrations during otherwise normal aging should not presently be considered equivalent clinical practices.
No major U.S. or European professional endocrine or urological guideline reviewed for this article recommends testosterone solely to maintain the testosterone concentration of younger adulthood in an otherwise healthy aging man.
A definitive reassessment of this conclusion would require long-duration randomized controlled trials specifically enrolling otherwise healthy aging men without established pathological hypogonadism and comparing maintenance of young-adult physiological testosterone concentrations against placebo or usual care.
Such trials would need to evaluate clinically meaningful outcomes including frailty, disability, cardiovascular events, venous thromboembolism, fractures, cognition, prostate outcomes, quality of life, functional independence, and mortality. They would also require sufficiently long follow-up to assess the cumulative consequences of decades of hormonal intervention.
Until such evidence becomes available, the position most consistent with contemporary U.S. and European specialist guidance is:
test when there is a clinical indication; diagnose hypogonadism using symptoms plus reproducibly low testosterone and appropriate etiological evaluation; treat demonstrated deficiency toward physiological concentrations; monitor treatment systematically; and do not equate normal age-associated testosterone decline with an established indication for anti-aging TRT.
Medical Disclaimer
This article is a narrative review intended for scientific and educational purposes. It summarizes and interprets published evidence and professional guidance concerning testosterone physiology, male hypogonadism, testosterone replacement therapy, and the proposed use of testosterone in healthy aging. It does not constitute individualized medical advice, establish a physician-patient relationship, or replace clinical evaluation by a qualified healthcare professional.
Testosterone therapy is a prescription medical treatment with recognized indications, contraindications, adverse effects, and monitoring requirements. Decisions regarding testosterone testing, diagnosis, or treatment should be based on an individual's symptoms and signs, appropriately repeated biochemical testing, relevant comorbidities, reproductive goals, concurrent medications, and applicable professional guidelines and regulatory requirements.
The findings and conclusions of this review should not be interpreted as recommending testosterone therapy for individuals without an established clinical indication.
Declarations
Funding
This work received no external funding. The author received no financial or commercial support for the preparation of this review.
Conflicts of Interest
The author declares no financial or non-financial conflicts of interest relevant to this manuscript.
Author Contributions
Ori Scott conceived the review topic and scope, defined the research questions and eligibility criteria, evaluated and interpreted the literature, critically revised the manuscript, and approved the final version. The author accepts responsibility for the accuracy, integrity, interpretation, and conclusions of the work.
Ethics Approval
Not applicable. This narrative review evaluates previously published literature and involved no recruitment of human participants, collection of identifiable personal information, or original intervention involving human or animal subjects.
Consent to Participate
Not applicable.
Consent for Publication
Not applicable.
Data Availability
No original participant-level dataset was collected or generated for this narrative review. The evidence discussed in the manuscript is derived from published peer-reviewed literature and authoritative professional and regulatory documents identified in the reference list.
Acknowledgments
None.
Declaration of AI-Assisted Technologies
An AI-assisted language tool was used during manuscript preparation to assist with organization, drafting, and language refinement. The author independently determined the scope and research questions, selected and evaluated the literature, interpreted the evidence, verified scientific claims and references, critically revised the manuscript, and approved the final version.
The AI-assisted tool was not treated as a scientific source, did not independently determine the inclusion or exclusion of evidence, and is not listed as an author. All scientific statements and references generated or suggested with AI assistance were subject to author review and verification against the cited primary sources or authoritative professional guidance.
The author accepts full responsibility for the accuracy, integrity, interpretation, conclusions, and final content of the manuscript.
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