Testosterone: Who Needs It and Who Doesn't?

The medical debate on mandatory screening plans for U.S. troops proposed by the Pentagon and the opinion of the scientific community.

The recent plan announced by Secretary of Defense Pete Hegseth to introduce mandatory testosterone screening tests for all U.S. military personnel aged 30 and over has reignited a lively debate in the international medical community. The initiative aims to identify potential deficiencies of the male hormone and offer replacement therapies, but the vast majority of experts and urological associations raise strong doubts about the clinical utility of mass screening on healthy individuals.

What is a "normal" level of testosterone?

Testosterone is the main male sex hormone, although it is also present in women at lower concentrations. The normal distribution of testosterone levels in the blood is extremely wide: it ranges from a minimum of 264 nanograms per deciliter to 914 ng/dL, according to Dr. Shalender Bhasin, professor of medicine at Harvard Medical School, who has been studying the subject for over forty years. The hormone is released in bursts, oscillating between 90% and 120% every 1–2 hours.

Levels can vary up to 15%–20% over the course of a single day: the peak is usually recorded in the morning, between 7:00 and 10:00. Furthermore, values can appear falsely low due to acute illnesses, trauma, or chronic stress from sleep deprivation.

The effects of aging and other factors

Contrary to what many believe, testosterone levels tend to peak between the ages of 20 and 30, then decrease by about 1% per year in healthy, lean men. However, most of the physiological decline is linked to weight gain and obesity, as noted by Dr. Brad Anawalt, an endocrinologist at the University of Washington.

Chronic conditions such as type 2 diabetes, the use of medications (opioids, anabolic steroids, glucocorticoids, and chemotherapeutics), genetic disorders, and chronic psychophysiological stress can further depress hormone levels.

The risks of mass screening

According to Dr. Helen Bernie of Indiana University and the American Urological Association (AUA), generalized screening on healthy adults would produce a very high number of false positives. Many men with seemingly low levels do not exhibit any clinical symptoms, and the mere numerical measurement can generate unwarranted anxiety or lead to unnecessary therapies.

Testosterone therapy: benefits and risks

Replacement therapy is regularly administered through transdermal gel, weekly or monthly injections, pills, or implanted pellets. While it is essential for treating severe pathological conditions (such as congenital hypogonadism or testicular failure), its cosmetic or preventive use carries significant risks:

• Fertility: Testosterone therapy suppresses sperm production, drastically reducing fertility (recovery may take months or may not occur).
• Red blood cells: It can cause polycythemia (an increase in blood viscosity), raising the risk of clot formation, stroke, and heart attacks.
• General health: About 2%–7% of men over 35 have a real deficiency; however, the vast majority of obese individuals or those with mild declines benefit primarily from lifestyle changes rather than medication.

When to test?

The guidelines of The Endocrine Society and the AUA recommend performing testosterone tests only in the presence of evident clinical symptoms (such as decreased libido, erectile dysfunction, loss of muscle mass, or reduced bone density) rather than as a routine preventive examination on asymptomatic individuals.