What is testosterone? Testosterone is a male sex hormone which is critical for a man’s sexual and reproductive development. It’s also produced by women but at much lower levels than men.

Testosterone is involved in the development of male sex organs and in puberty, but as men age their levels slowly drop. When there’s a severe fall in the hormone, men may seek out ‘testosterone replacement therapy.’ But it’s not clear how safe this treatment is and whether it comes with complications.

To find out more, an international group of researchers looked for links between high levels of testosterone in men and their risk of certain cardiovascular conditions such as thromboembolism (a blood clot which travels to another part of the body such as the lungs), heart failure and heart attack.

They didn’t actually measure the levels of testosterone in the group of men they were looking at – rather, they used the genetic data of the men to predict how much testosterone they had. That’s called their ‘endogenous’ testosterone – the amount you’d naturally expect them to produce.

By sorting the men into tiers based on their level of testosterone, they could see whether certain groups were more or less likely to experience problems with their heart. The men whose data were used in the research were mostly European and between the ages of 40 and 75.

The researchers found that higher levels of endogenous testosterone were linked to a higher risk of thromboembolism. It was also linked to heart failure and heart attacks. They say that this could be part of the reason why men have higher rates of heart disease compared to women of the same age.

Implications

It seems that genetic factors could increase a man’s testosterone and his risk of certain heart conditions. But that’s not something people can control.

The researchers are more interested in what these results suggest about testosterone replacement therapy ie although it may have benefits, there could be heart risks too.

They suggest that future research could look at treatments to lower endogenous testosterone in some cases, though researchers are still unravelling the complex interactions between it and other hormones the body produces.

Last Reviewed: 28/02/2020

© Norman Swan Medical Communications.



References

For reference: Luo, et al (2019). Association of genetically predicted testosterone with thromboembolism, heart failure, and myocardial infarction: mendelian randomisation study in UK Biobank. BMJ doi: 10.1136/bmj.l476.

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