Is it time to revise standard cut off of 300 ng/dL for testosterone deficiency in young men?

"Testosterone deficiency diagnosis has been performed traditionally in an age-indiscriminate manner," Alex Zhu, Department of Urology, University of Michigan, Ann Arbor, Michigan, and colleagues wrote in their study. "However, young and older men have different testosterone reference ranges."

Testosterone is critical for bone strength, muscle mass, sexual function, and hair growth. Low testosterone can lead to erectile dysfunction, poor concentration, low energy, low libido, and depression. Testosterone deficiency is the condition of low testosterone levels and one or more of these symptoms.

In men, male testosterone production declines with increasing age. Therefore, it is surprising that young men are investigated for testosterone deficiency with a similar cutoff of 300 ng/dL developed from samples of older men. The research team, therefore, aimed to describe normative total testosterone levels and age-specific cutoffs for low testosterone levels in men aged 20 to 44 years.

For this purpose, the researchers analyzed the 2011-2016 National Health and Nutrition Examination Surveys that surveyed nationally representative samples of the residents of the US. Men aged 20 to 44 years with testosterone levels were included. Those with hormonal medications, afternoon/evening laboratory values, and a history of testicular cancer or orchiectomy were excluded. Men were separated into 5-year intervals, and the researchers investigated the testosterone levels of each group for all men aged 20 to 44. The American Urological Association's definition of a "normal testosterone level" (the "middle tertile") was used to calculate age-specific cutoffs for low testosterone levels.

The study led to the following findings:

· The final analytic cohort consisted of 1,486 men.

· Age-specific middle tertile levels were 409-558 ng/dL (20-24 years old), 413-575 ng/dL (25-29 years old), 359-498 ng/dL (30-34 years old), 352-478 ng/dL (35-39 years old), and 350-473 ng/dL (40-44 years old).

· Age-specific cutoffs for low testosterone levels were 409, 413, 359, 352, and 350 ng/dL, respectively.

"Testosterone deficiency diagnosis has been performed traditionally in an age-indiscriminate manner," the researchers wrote in their study. "Young men, however, have difference testosterone reference ranges compared to older men."

The researchers, therefore, suggest integrating age-specific normative values and cutoffs into the evaluation of young men presenting with testosterone deficiency.

Reference:

Zhu A, Andino J, Daignault-Newton S, Chopra Z, Sarma A, Dupree JM. What Is a Normal Testosterone Level for Young Men? Rethinking the 300 ng/dL Cutoff for Testosterone Deficiency in Men 20-44 Years Old. J Urol. 2022 Oct 25:101097JU0000000000002928. doi: 10.1097/JU.0000000000002928. Epub ahead of print. PMID: 36282060.