Normal ranges for testosterone levels defined in landmark study

By Liz Meszaros, MDLinx
Published January 13, 2017

Key Takeaways

Reference ranges for total testosterone in men have now been established via a large study, and will help clinicians correctly diagnose hypogonadism, when applied to properly calibrated assays, according to these results published in theJournal of Clinical Endocrinology & Metabolism.

Precise diagnosis of many diseases, including hypogonadism, depend on accurate measurements of hormones. Yet, a lack of specific and accurate reference ranges of testosterone and standardization of hormone assays have made the diagnosis of hypogonadism difficult.

“Well-defined reference ranges are at the heart of clinical practice and without them clinicians can make erroneous diagnoses that could lead to patients receiving costly, lifelong treatments that they don’t need or deny treatments to those who need them,” said Shalender Bhasin, MD, of Brigham and Women’s Hospital, Harvard Medical School in Boston, MA and lead author of the study.

“Our data establish a reference range for testosterone. These data also show that variations in assays is an important contributor to variation in testosterone levels in cohorts from different geographic regions. Clearly we need standardization in all hormone assays,” Dr. Bhasin added.

Dr. Bhasin and colleagues included 9054 community-dwelling men who had previously undergone local assay of testosterone levels and were enrolled in the Framingham Heart Study, the European Male Aging Study, the Osteoporotic Fractures in Men Study, and the Male Sibling Study of Osteoporosis. Samples from 100 subjects from each of the four studies were sent to the CDC’s Clinical Standardization Programs at the National Center for Environmental Health. There, testosterone concentrations were measured using higher order liquid chromatography tandem mass spectrometry.

Results from both measurements were then used to generate harmonized values, from which researchers derived standardized, age-specific reference ranges.

For non-obese European and American men, aged 19 to 39 years, the harmonized normal range for testosterone was 264 to 916 ng/dL. Age-specific harmonized testosterone concentrations in non-obese men were similar across all cohorts. Researchers found a significant amount of inter-cohort variation in testosterone levels due to differences in assay techniques.

“Without harmonized reference ranges and standardized assays, tests can lead to misdiagnoses and unfortunately, this happens every day around the world,” said co-author Hubert Vesper, co-chair of The Partnership for the Accurate Testing of Hormones (PATH). “Now we have a reference range for testosterone, and it’s important that we take this into consideration in the tests that clinicians and patients depend on for accurate diagnoses.”

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