Testosterone is the primary sex hormone in men. It contributes to everything from the production of red blood cells and sperm, to bone density, fat distribution, muscle mass and strength.

One in four guys over thirty years old has low levels of this hormone, a condition known as “low-T”. While low-T is not unusual, a new study published in JAMA Network Open suggests that it can contribute to the development of more serious cases of COVID — the kind that may lead to hospitalization.

Men with low testosterone who contracted the virus were over twice as likely to be hospitalized than men with normal hormone levels, researchers at the St. Louis University School of Medicine and Washington University School of Medicine in St Louis found. What’s more, men who were treated successfully for their low-T condition before catching COVID did not run a higher risk of hospitalization.

Men with chronically low testosterone levels were getting sicker from COVID than men with normal levels.

On the face of it, this isn’t completely groundbreaking news. Researchers previously found that men who were hospitalized with COVID and had abnormally low testosterone levels (before getting COVID or after recovering) were getting sicker than men with normal levels. But the question remained: Was low-T a risk factor for severe COVID or the result of the condition?

To find the answer, cardiologist Abhinav Diwan, a professor at Washington University School of Medicine in St. Louis and co-author of the study, and his team needed to discover whether men with chronically low testosterone levels were getting sicker from COVID compared to men with normal levels.

By sifting through the records of two hospital systems in the St. Louis area, researchers found 723 men with COVID-19 whose testosterone levels were on record. Of those men, 427 were identified as having normal testosterone levels, 116 with low levels and 180 who were being treated successfully for low levels of the hormone. The men had confirmed cases of COVID in 2020 or 2021 and had low-T either before or after their infection.

“Low testosterone turned out to be a risk factor for hospitalization from COVID, and treatment of low testosterone helped to negate that risk,” said the study’s co-author, Sandeep Dhindsa, an endocrinologist at Saint Louis University, in a news release. He also noted that the risk “really takes off” when levels of testosterone in the blood are below 200 nanograms per deciliter (a metric unit equal to one tenth of a liter). The normal range is 300 to 1,000.

The findings excluded other possible causes for the increase in serious COVID cases. “This is independent of all other risk factors that we looked ate: age, obesity or other health conditions,” Dhindsa said. “But those people who were on [testosterone] therapy, their risk was normal.”

“Low testosterone turned out to be a risk factor for hospitalization from COVID, and treatment of low testosterone helped to negate that risk.”

Although the study’s findings don’t offer 100 percent proof that there’s a connection between serious COVID and low-T, it’s suggestive in the same way that other conditions such as heart disease, diabetes and chronic lung disease can increase the chance of requiring hospitalization for COVID.

“In the meantime, our study would suggest that it would be prudent to look at testosterone levels, especially in people who have symptoms of low testosterone, and then individualize care,” said Diwan. “If they are at really high risk of cardiovascular events, then the doctor could engage the patient in a discussion of the pros and cons of hormone replacement therapy, and perhaps lowering the risk of COVID hospitalization could be on the list of potential benefits.”

A decision to undertake testosterone replacement therapy should not be taken lightly. Men can suffer significant side effects such as:

  • The stimulation of prostate tissue, with perhaps some increased symptoms such as a decreased urine stream or an increase in frequency
  • An increased risk of developing prostate abnormalities
  • Enlarged breasts
  • An increased risk of blood clots
  • Acne or oily skin
  • Mild fluid retention

Because of these risks, the American College of Physicians (ACP) released new clinical practice guidelines for the use of testosterone therapy. It now advises doctors to prescribe testosterone only to treat sexual dysfunction in men experiencing age-related low testosterone. Have a conversation with your healthcare provider about the benefits and possible risks to testosterone therapy before agreeing to treatment.