Fact check: What is the normal range of testosterone levels in adult men?

1. Summary of the results

The normal range of testosterone levels in adult men is a topic of ongoing research, with various studies providing different reference ranges. According to ^[1], the normal range of testosterone levels in healthy nonobese men is between 264 and 916 ng/dL. Similarly, ^[1] reports that the 2.5th–97.5th percentiles for total testosterone in men aged 19–39 years are 264–916 ng/dL, which converts to approximately 9.2–31.8 nmol/L ^[1]. Other sources, such as ^[5] and ^[6], report a normal reference range of 300-1000 ng/dL (10.4-34.7 nmol/L) for serum total testosterone in adult men. However, it is essential to consider age-specific ranges, as reported by ^[2], which found that age-specific middle tertile levels of testosterone were 409-558 ng/dL for men 20-24 years old, 413-575 ng/dL for men 25-29 years old, 359-498 ng/dL for men 30-34 years old, 352-478 ng/dL for men 35-39 years old, and 350-473 ng/dL for men 40-44 years old ^[2]. Additionally, ^[3] reports age-specific cut-offs for low testosterone, indicating that normal testosterone in adult men is generally above ~12–15 nmol/L depending on age ^[3].

2. Missing context/alternative viewpoints

A crucial aspect to consider is the impact of metabolic components on testosterone levels, rather than just aging, as reported by ^[4]. This study found that testosterone levels peaked at 18 years and gradually declined to age 40, followed by a mild increase, and that metabolic components had a consistent negative correlation with testosterone levels ^[4]. Furthermore, the calibration of assays to a reference method and standard is vital for accurate measurements, as highlighted by ^[1] and ^[1]. The variation in reference ranges across different laboratories and studies also needs to be taken into account, as acknowledged by ^[6]. Additionally, the age-specific thresholds reported by ^[3] and ^[2] emphasize the importance of considering age when evaluating testosterone levels. The geographical and ethnic variations in testosterone levels, as reported by ^[4], which focused on Vietnamese men, also warrant consideration.

3. Potential misinformation/bias in the original statement

The original statement may be oversimplified, as it does not account for the age-specific variations in testosterone levels, which are crucial for accurate diagnosis and treatment. The statement may also be misleading, as it does not consider the impact of metabolic components on testosterone levels, which can lead to inaccurate assumptions about the relationship between aging and testosterone. Moreover, the statement may lack context, as it does not provide information about the calibration of assays and the variation in reference ranges across different laboratories and studies. The pharmaceutical industry and hormone replacement therapy providers may benefit from an oversimplified statement, as it could lead to increased demand for their products and services ^{[1] [5] [6]}. On the other hand, patients and healthcare providers may benefit from a more nuanced understanding of testosterone levels, as it would enable more accurate diagnosis and treatment ^{[2] [3] [4]}.