Does Low Testosterone Shorten Your Life? What 24,000 Men Revealed

Two men of 65 have their blood taken on the same morning. One has a testosterone level of 6 nmol/L. The other has 16. Both feel more or less fine.

Follow those two men, and thousands like them, for the next decade, and a clear pattern appears. The man with the very low level is more likely to die during that time, from any cause and from heart disease in particular.

That much is now well established. What it means, and what, if anything, you should do about it, is where most of the coverage goes wrong.

The largest analysis so far

In 2024, a team led by Bu Yeap at the University of Western Australia published the most detailed answer yet in the Annals of Internal Medicine. Rather than pooling published results, they gathered the raw data on individual men from 11 long-term studies across Australia, Europe and North America: 24,109 community-dwelling men, all followed for at least five years.

Two features make it stronger than earlier work. Testosterone was measured by mass spectrometry, the most accurate method, rather than the cheaper immunoassays most GP labs use. And having individual data allowed the researchers to look for thresholds rather than just averages.

What it found

• Below 7.4 nmol/L (213 ng/dL), the risk of dying from any cause rose, after adjusting for age, body mass index, and cardiovascular risk factors.
• Below 5.3 nmol/L (153 ng/dL), the risk of dying from cardiovascular disease rose.
• Above those levels, there was little difference. A man at 12 nmol/L was not at meaningfully higher risk than a man at 20.

That last point is the one most often lost. This is not a smooth "more testosterone, longer life" curve. The extra risk sits in men with genuinely, substantially low levels.

The researchers also found that a high LH, the pituitary signal telling the testes to work harder, was linked to higher mortality, and that the link between low testosterone and death held regardless of LH. In other words, it did not seem to matter whether the low testosterone came from the testes or the brain.

The other hormones in the analysis

Because the study measured several hormones at once, it also produced some less intuitive findings.

Higher SHBG went with higher risk. SHBG, the protein that carries testosterone in the blood, is often seen as harmless when it is high. In this analysis, men with lower SHBG had a lower risk of death and men with higher SHBG a higher one. The reason is not settled. SHBG rises with age, liver disease, low body weight and an overactive thyroid, so a high level may partly reflect frailty or illness. It is a marker worth interpreting rather than a number to chase. See what is SHBG?

Very low oestradiol was also a warning sign. Men with the lowest oestradiol levels had higher mortality. Men need some oestrogen, made from testosterone, for bone and cardiovascular health, which is one reason blocking it aggressively is unwise. We cover this in how to lower oestrogen in men.

DHT showed a U-shaped pattern, with both very low and very high levels linked to higher risk.

The question that matters: cause or marker?

Testosterone falls with illness. Men who are seriously unwell, carrying a lot of visceral fat, inflamed, sleeping badly or taking certain medications often have low testosterone as a result. So a low level may simply be a signal that something else is wrong, rather than the thing doing the damage.

Observational studies, however large, cannot fully separate those explanations. Adjusting for known risk factors helps, but it cannot account for everything.

That is why the trials matter more than the associations.

What the treatment trials show

The largest trial of testosterone treatment, TRAVERSE, published in the New England Journal of Medicine in 2023, gave testosterone gel or placebo to 5,246 men aged 45 to 80 with low testosterone and existing heart disease or high cardiovascular risk. Over roughly two years on treatment, testosterone did not increase major heart attacks, strokes or cardiovascular deaths compared with placebo.

That was reassuring on safety. But TRAVERSE was designed to show that treatment was not harmful, not that it saves lives, and it did not show a reduction in deaths. There is still no trial evidence that treating low testosterone makes men live longer. We go through TRAVERSE in detail, including the side effects it did find, in is TRT safe for your heart?

So the honest summary is this: very low testosterone is a warning sign worth taking seriously, and treating confirmed deficiency is reasonably safe for the heart, but nobody can yet promise that raising it will add years.

What a very low result should prompt

If anything, the mortality data are an argument for investigating low testosterone properly, rather than simply replacing it.

A result below about 7 or 8 nmol/L, confirmed on a repeat morning test, is not a borderline case. It deserves a search for the cause:

• LH and FSH, to show whether the problem is in the testes or the brain.
• Prolactin, because a raised level can point to a pituitary cause. See prolactin: the test that changes the diagnosis.
• Ferritin and transferrin saturation, to rule out iron overload. See haemochromatosis.
• Blood sugar, lipids, liver tests and thyroid function, because diabetes, fatty liver and thyroid disease all travel with low testosterone and all shorten life in their own right.
• A medication review, especially opioids, steroids and some psychiatric drugs.

Some of these, such as diabetes or a pituitary problem, matter more for your lifespan than the testosterone number itself. Treating the underlying cause, where there is one, is the priority.

What about modestly low levels?

Most men worried about their testosterone are not at 6 nmol/L. They are at 10 or 12, often with symptoms, often carrying weight around the middle. For them, the Yeap data offer little reason for alarm about lifespan, and the most useful changes are the ones that improve health generally: losing visceral fat, sleeping properly, cutting alcohol, building muscle. Those lower cardiovascular risk directly and tend to raise testosterone along the way.

See stubborn belly fat in men and does lifting increase testosterone.

Getting the measurement right

Because the risk sits at the very low end, accuracy matters. A single afternoon test after a bad night's sleep can easily read several nmol/L lower than your true level.

• Test in the morning, ideally before 10am, after a normal night's sleep.
• Avoid testing during or just after an acute illness.
• Repeat any low result before drawing conclusions.
• Ask about SHBG and free testosterone if your total level is borderline, because SHBG changes how much testosterone is available. See what is free testosterone?

Our guide to reading your blood test results explains each marker, and testosterone levels by age puts your number in context.

Common questions

Does low testosterone shorten your life?

Very low testosterone, below about 7.4 nmol/L, is linked to a higher risk of death in large studies. Whether the low testosterone causes that, or mainly reflects other illness, is not yet known.

Is there a testosterone level that is safe?

In the largest analysis, risk rose only below 7.4 nmol/L for all causes and 5.3 nmol/L for heart disease. Above those levels there was little difference in risk.

Will TRT help me live longer?

There is no trial evidence that it does. The largest trial, TRAVERSE, showed it did not increase heart attacks or strokes in men with low testosterone, but it did not show fewer deaths either.

Should I worry if my testosterone is 11 nmol/L?

Not about lifespan, based on current evidence. If you have symptoms, it is worth repeating the test and looking at sleep, weight and alcohol, which affect both testosterone and heart health.

What tests should follow a very low result?

A repeat morning test, then LH, FSH and prolactin to find where the problem lies, plus ferritin, blood sugar, lipids, liver and thyroid tests, and a medication review.

Sources: Yeap BB et al., Associations of testosterone and related hormones with all-cause and cardiovascular mortality and incident cardiovascular disease in men: individual participant data meta-analyses, Ann Intern Med 2024;177(6):768 · Lincoff AM et al., Cardiovascular safety of testosterone-replacement therapy, N Engl J Med 2023;389(2):107-17 · Educational only, not medical advice.

Keep reading: Is TRT safe for your heart? · What causes low testosterone · Prolactin: the test that changes the diagnosis · Testosterone and type 2 diabetes · Testosterone levels by age · How to read your blood test results