Mayo Clinic study reveals long-term negative effects of puberty blockers, challenging claims of reversibility

A new study conducted by 11 researchers at Mayo Clinic's largest campus south of Minneapolis has found that boys who take puberty blockers may suffer from fertility issues and a progressive degeneration or shrinkage of sex gland tissues known as atrophy.

The study, which examined the effects of puberty blockers on testicular cells and function, provides "unprecedented histological evidence revealing detrimental pediatric testicular sex gland responses to [puberty blockers]." Researchers found that mild to severe sex gland atrophy was one of the negative effects observed in the study participants, the Daily Mail reported.

The findings have led the authors to question the common claim that puberty blockers are "reversible."

The study examined 87 boys, including 16 gender dysphoric boys between the ages of 10 and 16, nine of whom were already on puberty blockers. All of the boys would eventually be put on blockers, and they began identifying as transgender girls between the ages of two and 15.

In one case, a 12-year-old boy who was treated with puberty blockers for 14 months experienced nearly 60% of his sex glands becoming "fully atrophied," and small clusters of calcium formed in his testicles. While several studies have linked these calcium clusters to cancer, it is not clear whether they are a risk factor by themselves.

The researchers also raised concerns about potentially permanent effects on fertility in boys treated with puberty blockers. In the case of a 14-year-old boy who had been on puberty blockers for more than four years, over 90% of his cells that were supposed to eventually produce sperm were developmentally arrested. These findings "raise a potential concern regarding the complete 'reversibility' and reproductive fitness" of the sperm germ cells, according to the researchers.

The researchers noted the lack of long-term studies on puberty blockers for gender dysphoric children, meaning that many of the drugs' effects, such as impacts on fertility, are still unknown. The study has been published on BioRxiv, a website hosted by the Cold Spring Harbor Laboratory, but has not yet been peer-reviewed. However, two-thirds of the papers published on BioRxiv are later published in peer-reviewed journals.

As detailed by the Daily Wire, Mayo Clinic's website page on puberty blockers does not currently warn about the extent of the side effects found in the study, stating that the drugs "don't cause permanent physical changes" and that puberty resumes when a child stops taking them.

The page describes puberty blockers as a way to "pause puberty," offering an opportunity to explore gender identity and plan for various issues that may arise in the future.