How much testosterone do men need?
Difficulty getting pregnant, fatigue, erectile dysfunction, and hair loss are all common symptoms of low testosterone. The advertisements of a booming testosterone industry constantly remind us of this, as do the food and fitness “hacks” touted by so many influencers. Professional opinions on the right testosterone levels for men vary widely, even among established experts. No wonder so many men obsess over their testosterone levels.
A new study aims to clarify what can be defined as low T – highlighting testosterone differences across ages. But some doctors wonder if the proposed change could further confuse tens of millions of men about where they stand and what to do with their testosterone.
Reach a new testosterone threshold
The new study, published in The Journal of Urology, argues that the standard threshold for clinically low testosterone levels in men needs to be adjusted. There is currently a single threshold for hypoglycemia: 300 nanograms per deciliter (ng/dL). But the study’s researchers argue that what counts as low T depends on a man’s age – an aspect previously overlooked because most of the data collected came from men over 40.
“Younger men have different testosterone baseline ranges than older men,” lead author Alex Zhu, DO, a urology resident at Michigan Medicine, said in a press release. “Our results suggest that we should use age-specific thresholds when assessing testosterone levels in younger men.”
The amount of testosterone a cisgender man has in his body – measured by a blood test – can change throughout his life, and most begin to experience a decline around age 30 to 40 when the glands that produce testosterone, including those in the testicles, begin to slow down. . Testosterone levels also drop when a man becomes a father, which may have an evolutionary root in the father giving up the hunt for new mates and becoming a family man instead, increasing his baby’s survival.
Before this decline begins, “normal” testosterone levels range from around 264 ng/dL to 916 ng/dL, according to the Endocrine Society. But different studies over the years have had slightly varying results on what normal ranges may be.
To learn more about normal testosterone levels throughout a man’s lifetime, Zhu’s team analyzed testosterone data from nearly 1,500 American men between the ages of 20 and 44. For each age group, they divided the testosterone levels they found into thirds: a low third of the population, a middle third, and a high third. They found that each year a man ages, his testosterone drops an average of 4.3 ng/dL.
Researchers have found that a testosterone level anywhere below 409 ng/dL – well above the current low testosterone threshold – is already low. for a man in his early 20s compared to the average T levels of his 20-24-year-old peers. This requires an update to low testosterone standards, Zhu’s team argues, and that the man should be considered to have low T and be eligible for insurance-covered testosterone therapy.
The Case for Age-Specific Testosterone Thresholds
With these results, clinicians could use age-specific low-T thresholds instead of a “one size fits all” approach, Zhu’s team says. Changing the official thresholds used by doctors — like the one set by the American Urological Association’s Testosterone Deficiency Guidelines, which came out in 2018 and likely won’t be updated for a few years — could make it easier for younger men who might need it to access testosterone therapy. Currently, insurance tends to only cover patients who fall below the standard threshold of 300 ng/dL.
But having lower testosterone levels than your peers — specifically, falling into the bottom third of testosterone levels for your age group — doesn’t necessarily mean you’ll have low testosterone symptoms or need treatment, says Kevin Campbell, MD, a urologist at the hospital. University of Florida Health did not participate in the study. Not everyone below 300 ng/dL has symptoms that can be attributed to low T, and not everyone above that level is without symptoms.
“We have to take it with a grain of salt,” says Campbell. Testosterone, like everything in the body, works in a complex system – although blood levels of testosterone can be high or low, the amount of T actually available to the body can be different, as testosterone is bound to other molecules that orchestrate whether testosterone is used or not.
“The concept of age-appropriate testosterone deficiency thresholds makes a lot of sense,” says Guillaume Paré, MD, a molecular epidemiologist at McMaster University in Ontario, Canada, who was not involved in the study. Paré worries, however, that testosterone deficiency is too often defined as a testosterone concentration below the 33rd percentile, essentially saying that one in three men will always be testosterone deficient. He doesn’t think that’s reasonable.
“By design, the current cutoffs classify one-third of men as having low testosterone. This is a large proportion of individuals and it might not reflect whether biologically there is too little testosterone”, explains Parè.
The risks and benefits of testosterone treatment
He thinks there should be stricter thresholds for low testosterone and fears that a diagnosis of testosterone deficiency at a young age could lead to overzealous long-term treatment with testosterone replacement therapy. , the potential side effects of which have yet to be studied in detail.
“The potential side effects of such treatment are not well understood,” Parè says. “Our own research suggests this may lead to an increased risk of prostate cancer, high blood pressure, and baldness,” he says, pointing to his 2020 study in the journal eLife.
The FDA has issued warnings that testosterone therapies may increase the risk of heart failure. However, its European equivalent, the EMA, notes that the data does not sufficiently confirm that testosterone therapy causes heart problems. The scientific jury has yet to determine the other effects of the therapy, including whether it improves or worsens sleep apnea, for example.
A 2022 study by Northwestern Medicine suggests that commercial brands providing testosterone therapy provide medication quickly without going through its pros and cons – for example, 83.3% of brands surveyed did not mention the possibility of testosterone therapy. an increase in the thickness of the blood.
“We need to make sure that there is a clear benefit for each patient who starts testosterone replacement therapy because it might not be as benign as sometimes assumed,” says Parè.
To avoid unnecessary treatment, it’s important not to interpret testosterone levels in isolation, says Richard Anderson, Ph.D., MD, co-director of the Center for Reproductive Health at the University of Edinburgh in Scotland, who n did not participate in the study. to study. Whether the man is showing symptoms, has other health conditions, has been under recent stress, or has undergone lifestyle changes that may affect his testosterone levels, such as increased smoking or alcohol, it is imperative to interpret blood testosterone levels in context.
Sometimes patients are able to wean themselves off testosterone replacement therapy, although they probably all have the same symptoms that brought them to therapy. And stopping high-dose testosterone therapy can cause drastic withdrawal symptoms.
“We know the consequences of very low levels, and it’s clear that treatment is beneficial,” Anderson says. “But that’s not the case for less marked low levels, and overtreatment should be avoided, as it is very difficult to stop treatment later.
