Generally, experts are wary of universally screening men for low testosterone because testosterone measurements can be highly variable—and unhelpful. Levels can dip for a number of different reasons, including age, time of day, obesity, illness, physical stress, poor sleep, trauma, and various medications. Moreover, the conditions that can cause clinically significant low testosterone—a condition called male hypogonadism—are rare, affecting 1 percent of men at most. They include genetic conditions and problems with the pituitary gland.

Given the complexity, experts recommend that evaluations be prompted by patients self-reporting symptoms. In those cases, doctors use repeat testing and comprehensive evaluations to come to a firm diagnosis of male hypogonadism. With that being the current norm, researchers aren’t sure exactly what the military’s new universal screen will yield.

According to the new data, a large portion of the military may face alarming results. From the Army members in the survey, the weighted mean for morning total testosterone was 405 ng/dL. The Pentagon’s clinical guidance uses a threshold of less than 300 ng/dL for low testosterone, in line with recommendations from the AUA. Using that cutoff and extrapolating the data to the entire Army population, the researchers estimate that about 26 percent of active-duty Army service members would get a test result suggesting low testosterone.

The Centers for Disease Control and Prevention has a harmonized reference cut-off that’s a little lower, at 264 ng/dL. With that threshold, about 15 percent of Army service members would be estimated to have a low testosterone result.

Screening risks

As expected, the likelihood of low results scaled with weight and age; the higher the age and/or higher the BMI, the greater the odds of having a testosterone reading under either threshold. Of men under age 30, 19.5 percent had a low measurement, while 33 percent of men aged 30 and older had low levels.