Hormone levels and symptoms not correlated
These recommendations are based on the fact that the correlation between symptomatic hypogonadism and testosterone levels is poor, meaning that other factors should be considered when considering whether symptoms relate to deficiency. However, Dr. Zhu contended that objective evidence of a low level of testosterone is useful in considering the role of hormone deficiency.
“Even if one were to choose a different cutoff, our age-specific normative testosterone ranges still provide young men and their physicians a framework for counseling,” according to Dr. Zhu. Because of the risk of nonspecific symptoms, such as fatigue and diminished physical performance, he called for “a high index of suspicion for testosterone deficiency even when evaluating younger men.”
Considering the diurnal fluctuations, the single measurement employed to calculate normative ranges is a limitation of this study, the authors acknowledged. They cited data suggested that up to 35% of men classified as hypogonadal on the basis of a single testosterone assay will not meet the same criterion even if evaluated in the subsequent 24 hours. It is for this reason that guidelines typically recommend measuring testosterone at least twice or with more than one type of assay.
Up until now, decisions about testosterone deficiency have been with a one-size-fits-all approach, but it has long been known that patient age is a variable in determining average levels of this hormone, Dr. Zhu reported. For this reason, he predicted that these data will have clinical utility.
“We believe that our new cutoffs play an important role in evaluating younger men presenting with symptoms [of testosterone deficiency],” Dr. Zhu said. “However, clinicians should still remember that these symptoms have causes other than low testosterone, so we cannot only focus only on testing testosterone.”
However, given the lack of correlation between symptoms and testosterone levels, this area remains controversial.
Value of tertile cutoffs questioned
Two independent experts challenged the methodology and conclusions of this study.
Victor Adlin, MD, an associate professor emeritus at Temple University, Philadelphia, questioned tertile levels as an approach to defining normal.
“The authors propose unusually high cut-points for a definition of low testosterone in young men,” said Dr. Adlin, whose published a comment on age-related low testosterone in response to 2020 guidelines issued by the American College of Physicians. He is concerned that these data could lead to overtreatment.
The authors “imply that [these data] would justify treatment with testosterone in many young men with symptoms such as fatigue, depression, and lack of vigor, whose relation to low testosterone is controversial,” he said in an interview. “Trials in older men have failed to show a clear response of such symptoms to testosterone therapy.”
The first author of the 2018 Endocrine Society guidelines, Shalender Bhasin, MB, BS, director of a research program in aging and metabolism at the Brigham and Women’s Hospital in Boston, was even more skeptical.
“The whole premise of generating cutoffs for a disease or condition based on the middle tertile is just so far off and irrational,” he said. A coauthor of a 2017 study designed to define harmonized testosterone reference ranges by decade of age (that he described as providing “a much larger sample size and a wider age range” than this current study), Dr. Bhasin did not see any value in the NHANES-based analysis.
Rather, he called for an effort “to dispel this ill-conceived idea that could mislead young men to think they need testosterone treatment when they are healthy.”
Dr. Zhu and Dr. Adlin reported no potential conflicts of interest. Dr. Bhasin reported financial relationships with AbbVie, Eli Lilly, Novartis, Regeneron, and Takeda.