The Cutoff for Low T Diagnosis: Not So Black and White After All

Low T is often thought of by most younger men of 40 years and under as a problem for “old guys” and something they don’t need to worry about. However, an increasing number of men aged 40 and younger are now also being seen by doctors with the telltale sign of Low T—a significant decrease in vitality far too early in life.

Here’s the problem…

Despite the recognized increase in Low T cases occurring in younger men, there likely are far more cases going undiagnosed due to “normal” testosterone levels—their medical provider used the testosterone ranges appropriate for older men when evaluating the younger men’s test results. 

(Learn more about how Low T is diagnosed here.)

A young man in a green t-shirt and a white towel around his neck looks at the camera. Does he know the Low T cutoff is different for younger men?

Different Low T Cutoff Points for Different Age Groups?

Alex Zhu of the University of Michigan, Ann Arbor​​ and Lead author of a recent research project on the subject of Low T diagnoses across age groups had this to say:

“Young men have different testosterone reference ranges than older men. Our findings suggest we should be using age-specific cutoffs when assessing testosterone levels in younger men.”

So, what defines “low”?

The American Urology Association (AUA) says low blood testosterone is less than 300 nanograms per deciliter (ng/dL). 

But, is this for all men across all age groups? 

Logically, that can’t be. Low testosterone is not a one-size-fits-all condition. 

For starters, younger men require more testosterone to fuel their system due to a more active lifestyle, and they have not started the natural age-related decline in testosterone production yet. 

The above 300 ng/dL figure was calculated for older men who were already well into that decline. 

These groups naturally have different “normal” levels to begin with, and men not yet in the decline must be measured against a standard that excludes the age effect. 

Simply put, the established black-and-white cutoff point used for low testosterone diagnosis is not likely accurate for men in their mid-forties or younger.

The Research on Low T Cutoff Points

The researchers from the University of Michigan Department of Urology analyzed data from nearly 1,500 men, aged 20 to 44 years, from a nationwide health study titled the National Health and Nutrition Examination Survey, or NHANES.

Researchers evaluated the range of the subjects’ testosterone levels in five-year age groups. The middle one-third of the testosterone level distribution for each five-year age group was defined as the normal range. Values in the lowest one third were used to calculate age-specific cutoff thresholds that would indicate low testosterone levels for that age group.

The test results predictably demonstrated that testosterone norms and Low T cutoff points decreased at older ages. For the age range of 20 to 24 years, the cutoff point for low testosterone was found to be 409 ng/dL, while 350 ng/dL was the cutoff for men aged 40 to 44 years old.

The full experiment’s results showed that every one-year increase in age resulted in a 4.3 ng/dL decrease in testosterone.

Read more about this research project here.

What the Research Means

Dr. Zhu and his fellow researchers conclusions follow:

“In today’s age of personalized medicine, clinicians can now use age-specific testosterone levels to evaluate young men instead of relying on a ‘one size fits all’ approach.”

The researchers also commented that further research results supporting the age-specific cutoffs had the potential to affect insurance policies that require testosterone levels to fall below the “older men” standard of 300 ng/dL in order to cover treatment. 

Being examined by your medical practitioner and diagnosed for low testosterone at a young age could be the first step in getting needed medical treatment or be the catalyst that leads to beneficial lifestyle changes you can take action on today.

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(Augie) Juan Augustine Galindo Jr. MPAS, PA-C

(Augie) Juan Augustine Galindo Jr. MPAS, PA-C started his career in healthcare as a fireman/paramedic in West Texas where he served on the Midland Fire Department from 1998-2004.   He became interested in testosterone treatment after seeing how hormone replacement doctors helped those suffering from low testosterone.   After graduating from the Texas Tech Health Sciences Center Physician Assistant Program, he moved to DFW where he currently lives with his wife and three children.

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