TRT Is Not an Anti-Aging Treatment

Testosterone declines slowly in most men from middle age onwards. That is a normal biological trajectory, not a disease, and treating it as one is the basis of a very large commercial market.

Somewhere between his thirties and his sixties, the average man's testosterone drifts downwards. The rate is slow — the decline over a decade is small compared with the variation between individuals at any age — and most men stay within the normal range for their entire lives. Some do not, and some of those develop symptoms. That last group has a treatable condition. The rest have got older.

The distinction sounds pedantic. It is the whole argument.

What age-related decline actually is

Longitudinal studies following the same men over years consistently show a gradual reduction in total testosterone with age, with free testosterone falling somewhat faster because SHBG tends to rise. The change is measurable at a population level and modest at an individual level.

Much of the decline is also not purely about age. Weight gain, developing insulin resistance, accumulating chronic illness, medication burden, reduced activity, worsening sleep and increasing prevalence of sleep apnoea all track with age and all independently lower testosterone. Studies that adjust for health status find a smaller age effect than studies that do not. In a man who has gained thirty pounds, developed apnoea and stopped exercising between forty and fifty-five, attributing the whole change to the calendar is a stretch.

Hypogonadism, by contrast, is defined by consistently low measured testosterone on repeat morning testing, together with clinical features that match, with other causes considered. It has identifiable causes — testicular failure, pituitary disease, genetic conditions, opioid use, significant obesity, previous anabolic steroid use. It is diagnosed, not assumed.

What the evidence supports, and what it doesn't

Testosterone in older men has been studied. It has not been studied casually — there have been coordinated randomised trials specifically examining older men with low levels for their age and no classical cause.

The pattern of findings, described honestly: some measures showed modest improvement. Sexual function was the domain where effects were most consistently detectable, though the size of the effect was smaller than the marketing implies. Effects on mood were small. Effects on vitality and physical function were inconsistent, and in several analyses did not reach a level that would be obvious to the man himself. Effects on cognition were not demonstrated.

Set against that, no trial has shown that treating age-related decline extends life, prevents the diseases of ageing, or restores anything that could reasonably be called youth. The trials were also not long enough or large enough to settle the long-term safety questions for this population, which is a separate limitation and an important one.

The professional guidelines reflect all of this. The major endocrine societies do not recommend routinely offering testosterone to older men purely on the basis of an age-associated decline. They recommend diagnosing hypogonadism properly and treating it where it exists. That is not conservatism for its own sake — it is what the evidence supports.

How the market blurs the line

The commercial version of this subject rarely says anything factually false. It works by omission and by framing.

The questionnaire

Nearly every direct-to-consumer hormone service opens with a symptom checklist: tired, low libido, gaining weight, sleeping badly, less strong than you were, less motivated. Almost every man over forty answers yes to several. The questionnaire is not a screening instrument in any meaningful sense — it flags a huge share of the population, including men whose testosterone is entirely normal and men whose symptoms are caused by sleep apnoea, depression, thyroid disease or chronic sleep restriction. Those overlaps are set out in our article on low testosterone symptoms.

The vocabulary

"Optimising" your levels. "Peak performance." "Reclaiming your edge." None of these are clinical concepts. There is no established therapeutic target above the normal range, and no evidence that pushing a man from the middle of the range to the top of it produces benefit. The language exists because "you are within the reference range and do not have a hormone disorder" does not convert.

The threshold that moves

Because reference ranges differ between laboratories and assays, a service can select a cut-off that classifies more men as candidates. A result described as "low-normal but suboptimal for a man your age" is a marketing sentence, not a diagnosis.

The single test

One non-fasting afternoon sample, no repeat, no LH or FSH, no thyroid, no prolactin, no baseline haematocrit. That is enough to produce a low-looking number in a man whose morning level would be normal. This pattern is part of a wider set of behaviours described in our piece on spotting a prescription mill.

What it costs the man who didn't need it

Prescribing testosterone to a man with normal levels is not a harmless placebo with a monthly fee.

His own production shuts down. Exogenous testosterone suppresses the hypothalamic-pituitary-gonadal axis. Within months of starting, his testes are producing considerably less than they were. This is not a side effect — it is how the feedback loop works.

His fertility is suppressed. Sperm production falls substantially in most men on testosterone and stops entirely in a proportion. Recovery after stopping is usual but variable, slower with longer use, and not guaranteed. A man in his thirties who was never asked whether he wanted children has been placed in that position without being told. This is the most consequential harm in the whole picture and it has its own article: TRT and fertility.

He becomes dependent on an external hormone. Having suppressed his own axis, stopping means a period — sometimes a long one — in which his own production has not recovered and he has no external supply. Men in that window often feel considerably worse than they did before they started. Some interpret that as proof they needed treatment all along. It is more often evidence of suppression.

He accepts monitoring obligations for no benefit. Haematocrit, PSA, blood pressure and the rest all still apply. The risk and monitoring picture does not shrink because the indication was weak.

And whatever was actually wrong goes unexamined. The apnoea, the depression, the thyroid, the alcohol, the five hours a night. Those had treatments. They were not looked for.

What to do with the symptoms instead

The symptoms are real. Men are not imagining the fatigue or the loss of drive. Taking them seriously means investigating them rather than assigning them to the most heavily marketed explanation.

That means a proper history and examination. Morning testosterone, repeated, with LH, FSH, prolactin, thyroid function, full blood count and metabolic markers alongside. Screening for sleep apnoea. An honest conversation about mood, alcohol and sleep. And, in a great many cases, attention to the unfashionable things — resistance training, sleep duration, weight, alcohol intake — which have better evidence behind them for this symptom cluster than any hormone does in a man whose levels are normal.

If that assessment finds hypogonadism, treatment is a reasonable conversation. If it finds normal levels, the correct answer is that testosterone is not indicated — and a service that cannot say that sentence is not a clinical service. Our full guide to testosterone replacement therapy covers where the treatment genuinely belongs, and our hormone health service page explains how assessment works here — including the outcomes that do not end in a prescription.