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Researchers define normal ranges for testosterone levels in young men
Recent findings published in The Journal of Clinical Endocrinology & Metabolism showed that the harmonized normal range for testosterone levels in young, healthy European and American men is 264 ng/dL to 916 ng/dL.
“Hypogonadism in men is a syndrome characterized by a set of symptoms and signs of androgen deficiency that occur in association with consistently low circulating testosterone levels. The reference ranges provide the basis for demarcating ‘low’ from ‘normal’ testosterone levels, and are, therefore, essential for making the diagnosis of hypogonadism,” Thomas G. Travison, PhD, of the Institute for Aging Research, Hebrew Senior Life, and Harvard Medical School, and colleagues wrote. “The distribution of testosterone concentrations could vary in men from different regions due to inter-assay or inter-laboratory differences, or biological or environmental factors.”
The researchers compared testosterone concentrations based on 9,054 men who had participated in four cohort studies: the Framingham Heart Study, the European Male Aging Study, Osteoporotic Fractures in Men Study and Male Sibling Study of Osteoporosis. The researchers generated normalizing equations using Passing-Bablok regression, then used those equations to generate harmonized values and derive age-specific reference ranges.
For healthy men without obesity aged 19 to 39 years, the researchers reported that the 2.5th percentile testosterone level was 264 ng/dL, the 5th percentile was 303 ng/dL, the 50th percentile was 531 ng/dL, the 95th percentile was 852 ng/dL and the 97.5th percentile was 916 ng/dL. Harmonized, age-specific testosterone levels were similar across cohorts.
“These data demonstrate the feasibility and potential value of generating harmonized reference ranges for testosterone concentrations, whose serum total testosterone concentrations have been measured in a CDC-certified laboratory,” the researchers wrote. “There was a remarkable concordance in age-adjusted harmonized testosterone levels among men in four geographically distinct cohorts, suggesting that inter-cohort variation may be influenced by inter-assay variation. Further studies of the distribution of testosterone concentrations in other racial and ethnic groups and in populations in other regions of the world are needed to demonstrate the applicability of these ranges to broader populations of men in different regions of the United States and the world.” – by Andy Polhamus
Disclosure: Travison reports no relevant financial disclosures. Please see the full study for a list of all other researchers’ relevant financial disclosures.