'Low T' and Blood Clots: A Possible Change in Thinking

Testosterone therapy and venous thromboembolism blood clot disorder not likely linked


Some men with low testosterone might be tempted to hold off on treatment due to concerns about raised health risks. But for one common concern, those raised risks might not exist.

Despite past concerns, a new study found that testosterone therapy did not increase the risk for blood clots in the veins, called venous thromboembolism (VTE).

"In 2014, the Federal Drug Administration required manufacturers to add a warning about potential risks of VTE to the label of all approved testosterone products. The warning, however, is based primarily on post-marketing drug surveillance and case reports," said lead study author Jacques Baillargeon, PhD, of the University of Texas Medical Branch at Galveston, in a news release.

E. David Crawford, MD, a professor of surgery, urology and radiation oncology at the University of Colorado in Denver, told dailyRx News that concerns surrounding testosterone replacement therapy (TRT) continue to spark heated debates.

"I see commercials on television from lawyers soliciting men who have side effects from TRT to contact them," Dr. Crawford said. "A number of flawed reports popularized these potential risks. The authors refute the apparent risk of VTE. Every drug or treatment has risks."

VTE is the dangerous combination of two medical events: a blood clot in a deep vein (often in the leg) and the dislodging of that clot and its movement to the lungs.

According to the International Society on Thrombosis and Haemostasis, there are an estimated 10 million cases of VTE around the world each year. The condition is thought to cause between 100,000 and 300,000 deaths each year in the US alone.

Testosterone is the male sex hormone. It plays a part in male development. Low testosterone can raise men's risk of heart disease, diabetes and sexual dysfunction, among other problems. Low testosterone is often treated with prescription testosterone drugs.

To explore the potential link between VTE and testosterone therapy, Dr. Baillargeon and colleagues looked at 2007 to 2012 data from the Clinformatics DataMart insurance database to find men aged 40 or over.

A total of 7,643 cases of VTE were identified in this group. These cases were each matched to three "controls," or men with similar characteristics (like age, location and underlying conditions) but who didn't have VTE. A total of 22,929 controls were identified.

Dr. Baillargeon and team found that men who filled a prescription for testosterone therapy had no greater risk of developing VTE than those who did not. This proved true for all types of testosterone treatment — testosterone creams, patches and injections — included in this study.

These researchers also saw no differences in risk among men who received testosterone therapy 15, 30 or 60 days before they were diagnosed with VTE.

"It is important to acknowledge, for a man who has medically-diagnosed low testosterone, that there are clear risks to not receiving testosterone therapy, including osteoporosis, sexual dysfunction, increased amounts of fat tissue, decreased lean muscle mass, possible metabolic syndrome and cardiovascular disease," Dr. Baillargeon said. "It's also important to note that further research needs to be conducted to rigorously assess the long-term risks of testosterone therapy."

This study was published online July 20 in the journal Mayo Clinic Proceedings.

One of the study authors received payments from a number of pharmaceutical companies, such as Bayer, Eli Lilly and Pfizer. The University of Texas Medical Branch and the National Institutes of Health funded this research.