Testosterone and Blood Clots: Study Finds No Link

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Nelson Vergel

Founder, ExcelMale.com
A new study from The University of Texas Medical Branch at Galveston of more than 30,000 commercially insured men is the first large comparative analysis to show that there is no link between testosterone therapy and blood clots in veins. The study found that middle-aged and older men who receive testosterone therapy are not at increased risk of this illness. The findings are detailed in Mayo Clinic Proceedings.

Venous thromboembolism is a disease where blood clots form in the veins and cause blockages. The most common forms of VTE are deep vein thrombosis, which occurs often in the legs and pulmonary embolism, which is a clot in the lungs. VTE is the third most common cardiovascular illness, after heart attack and stoke.

"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," said Jacques Baillargeon, professor of epidemiology in the department of preventive medicine and community health and lead author of the study. "The warning, however, is based primarily on post-marketing drug surveillance and case reports. To date, there have been no published comparative, large-scale studies examining the association of testosterone therapy and the risk of VTE."

As a result of this conflicting evidence and the broad media attention it has received, there are many men with medically confirmed low testosterone who are afraid to receive testosterone therapy and there may be physicians who are reluctant to prescribe testosterone therapy based on this conflicting information.

The case-control study included 30,572 men 40 years and older who were enrolled in one of the nation's largest commercial insurance programs between Jan. 1, 2007 and Dec. 31, 2012. Cases were defined as men who had a primary diagnosis of VTE and received an anticoagulant drug or an intravascular vena cava filter in the 60 days following their diagnoses. Cases were matched with three control subjects on age, geographic region, diagnosis of low testosterone and diagnosis of any underlying pro-clotting condition.

The researchers found that having a prescription for testosterone therapy was not associated with an increased risk of VTE. In addition, none of the specific routes of administration examined—topical creams, transdermal patches or intramuscular injections—were associated with an increased risk. There were no differences between men who received the therapy 15, 30 or 60 days before being diagnosed with VTE.

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Defy Medical TRT clinic doctor


I wonder if the men in this study also used aromatase inhibitors such as anastrozole. Blood clots are a known (rare) side effect of anastrozole and it's my belief that people blame blood clots on testosterone when the real culprit is the aromatase inhibitors that are prescribed alongside testosterone.
I think high hematocrit and estradiol may play a role in increased clotting. I am glad to see a study that shows that this problem is not as common as we feared.

Thanks for alerting this to us, Nelson. I DIDN'T REALIZE THAT GLUECK HIMSELF IS ONE OF THE AUTHORS OF THE STUDY. Does not this study essentially reverse his previous findings? What about the remaining concern for those few that have familial predisposition for thrombophilia and out of that (the supposed 2%), an even smaller minority that would be at risk for a full-blown DVT/PE? Nonetheless, for the 98%, the study definitely bolsters confidence that clotting disorders are highly unlikely. In my case, I do not have a clear cut case of familial thrombophilia and the causes for my two clotting episodes back in 2012 remain unknown. Glueck's advice was originally to stay away from exogenous T regardless. It would be interesting to get his opinion now.

I keep marching on, looking for more answers and solutions. In the meantime, my natural T levels aren't doing too bad (last total T was 609, free T 64.8).
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I for one have had vascular issues since starting trt. Ive had varicose veins for years but they worsened it seems since I started. Had endoscopic laser ablation done twice and have brawny edema on both legs. According to the interventional radiologist I have evidence of DVT in one leg that I never knew about or had symptoms from. However, all this is tempered by the fact that the radiologist also suspects I blew out my lower leg vein valves from straining too much lifting weights so the fact I'm taking testosterone is circumstantial at best in the development of vascular issues.
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