It is considered the male hormone, but women also make testosterone – a healthy level is therefore important for both genders. In this context, a study now shows that testosterone production in men and women is based on different genes and that the hormone affects the risks of developing metabolic and cancer diseases in different ways. The results therefore have significance for the artificial changes in the hormone balance, say the scientists.
They are called sex hormones: Put simply, testosterone makes men and estrogen makes women. However, it is known that both hormones are also formed in the body of the opposite sex and have functions. In men, testosterone is produced in comparatively large amounts in the testes. In women, on the other hand, it occurs primarily in the ovaries. The effects that testosterone triggers in the body are complex and still not fully understood. In men, testosterone provides, among other things, for muscle building and the sex drive. In order to combat tiredness and listlessness, the dwindling testosterone level is often artificially increased, especially in older men. But testosterone substitution is also possible in women. A favorable level also promotes libido in the female gender, according to studies.
However, artificial hormone doses are tricky – because testosterone has two sides: Although it promotes some desirable aspects, it can also increase the risks for certain diseases, as has been shown by previous research. For this reason, natural hormone levels are artificially lowered in some cancers. But there are still many open questions on this topic. For example, it is unclear to what extent natural differences in testosterone levels in humans are linked to tendencies to certain diseases and also to which hereditary system the differences in hormone levels in men and women are based.
On the trail of the basics of hormone levels
To gain new insights, the researchers led by John Perry from the University of Cambridge have now carried out a so-called genome-wide association study. It is a process for identifying links between certain genetic peculiarities and physical characteristics. In the current case, this means that the researchers looked for hereditary factors that are linked to a comparatively high level of testosterone in men and also in women. A British biobank served as the database. It contains the genetic information of 425,097 participants. In addition to health data, the testosterone level of these people is also known.
The results made it clear that the level of the hormone is not influenced by just a few hereditary factors, but has a complex genetic background: The researchers identified 2571 genetic variations that are related to differences in the levels of the sex hormone testosterone and its binding protein. There were clear differences between the sexes. This means that the regulation of the hormone has a different genetic basis in women and men.
In order to shed light on the link between testosterone levels and disease risks, the researchers then carried out a so-called Mendelian randomization with their data. It is a statistical method for determining the influence of risk factors on diseases using the variation of genes of known function.
Good or bad – depending on the gender
As the scientists report, it became apparent that a genetically elevated testosterone level in women is linked to a 37 percent increased risk of developing type 2 diabetes. It shows how different the hormone can be between the sexes: In men, a genetically high level of testosterone lowers the risk of diabetes by 14 percent. The hormone apparently has a similarly unfavorable effect on the risk of breast and uterine cancer in women.
As the researchers emphasize, a particularly interesting result was that women with a genetically high level of testosterone apparently increased the risk of so-called polycystic ovarian syndrome (PCOS) by 50 percent. This is one of the most important causes of unfulfilled desire to have children. “Our findings that genetically higher testosterone levels increase the risk of PCOS in women are important to understand the role of testosterone in the development of this common condition,” said Perry. The hormone apparently has a similarly unfavorable effect on the risk of breast and uterine cancer in women.
According to him, another message from the study concerns men: a higher testosterone level means that they have a slightly higher risk of developing prostate cancer, as the statistical evaluations show, “Testosterone-reducing therapies are often used to treat prostate cancer. So far, however, it was uncertain whether a naturally lower testosterone level would also protect against the development of prostate cancer. In this context, our results have now contributed to an understanding of the risks and benefits of hormone therapies, ”says Perry.
His colleague Katherine Ruth from the University of Exeter adds: “Our results underscore the importance of considering men and women separately,” says the scientist. As for the treatments with testosterone, she says: “Caution is advised. Further studies that show the effect of testosterone on other problems, such as cardiovascular diseases, should now follow, ”says Ruth.
Source: University of Cambridge, professional article: Nature Medicine: 10.1038 / s41591-020-0751-5