Guest Blog: Puberty Blockers, Trans Youth, and Bone Loss

Another thought-provoking article from Open Minded Health, this time a review on an article that examines a possible down-side of puberty blockers.

Puberty blockers (“GnRH agonists”) can be extremely helpful for transgender (trans) and gender non-conforming (GNC) children and their families. They are used to “pause” puberty. The pause allows time for negotiation, thought, and discussion. Schools need to be contacted and negotiated with. Families may need time to ask questions and do their own research. The trans/GNC young person is relieved from the distress of an unwanted puberty.

Simply, puberty blockers work by telling the body “It’s not time for puberty yet — stay as a pre-puberty body”. That message keeps ovaries and testes from producing their sex hormones. For young people just beginning puberty, it’s like pressing “pause” on puberty. But they can also be used post-puberty to reduce overall sex hormone levels. So “puberty blockers” can be used as testosterone blockers in trans women. They’re not used often in the United States that way because they’re expensive, but they’re very effective.

Puberty blockers are generally safe. They have been in use for a long time for children with precocious puberty. However there is one unknown that’s been a concern for both parents and their children: Bone health.


The time when we build the most bone density is in puberty, and it’s in response to sex hormones. The amount of bone we build in puberty and adolescence is associated our chances of osteoporosis and bone breaks later in life. The more bone with build, the less likely we are to have weak and brittle bones as we age. So physicians and scientists were left with a question: Will lowering sex hormone levels during this crucial period prevent them from building the bone they need for later in life?

All of that background brings us to this week’s article. Finally, a team in the Netherlands has published on the effects of puberty blockers on bone mineral density.

Who did they study, and what was the specific treatment? This paper reports data from 34 trans/GNC youth. These youth started puberty blockers (triptorelin) at 14-15 years old, added estrogen/testosterone (oral estradiol/IM testosterone) at 16, had genital surgery, and were studied at the age of 22. In total, they had an average of 1.3-1.5 years on puberty blockers alone and 2.2-3.1 years on combined therapy.

Those ages are important. They’re the standard years for treatment in the Netherlands. But note that 14-15 years old is past puberty. Despite that, after their natal puberty they had over a year of suppression of sex hormones. Could that have had an effect on their bones?

To find out, these researchers scanned them with DEXA scanners, similar to the ones used for adult screening. They were scanned when they started puberty blockers, when they started hormone therapy, and at age 22. Their bone mineral density was compared to the average densities of cis people of their natal gender. That is, trans men were compared to cis women and trans women were compared to cis men. This does make some sense. They were asking, in essence, “Did the treatment cause harm that would not have happened if we hadn’t treated?”

The answer is complicated.

• Trans women in this study had low bone mineral density for their age. However, they also had low bone mineral density at the start of the study. The researchers point out that dysphoria may prevent them from playing and doing weight-bearing exercise. It’s hard to say whether their low bone mineral density was because of the puberty blockers or because they had low density to begin with.
• Trans men in this study did not appear to have low bone mineral density.
• Both groups stopped gaining bone mineral while on puberty blockers alone. They gained density after being on hormone therapy. This means they were behind their peers, but not necessarily that they lost density over that time. It appears to have “paused”.
• Since the study only went to age 22, the long term effects on their fracture risk are unknown.

The researchers state that the study should be interpreted cautiously. I agree with their reasons, and I’m glad they pointed them out. The comparisons to people who shared their natal sex may not have been appropriate. The sample size was small, making it hard to find true statistical differences. They didn’t measure other factors, such as how much calcium they were eating. Lastly: the puberty blockers were given after puberty was basically done. So the blockers weren’t actually preventing natal puberty, as we hope they’ll be used to do in the future.

So what does all this mean to young trans people on puberty blockers, or who have been on puberty blockers? Not a lot that’s substantially different from everyone else. Get enough calcium in your diet. Get some sun to get o Do weight-bearing exercise if you can. And consult your physician if osteoporosis or other bone-related disorders or diseases run in your family.

Regardless, this study helps to shed light on what happens during puberty blocker treatment. They’ll be continuing to follow up with the individuals in the study. I’m looking forward to it.
The study was “Bone mass in young adulthood following gonadotropin releasing hormone analogue treatment and cross sex hormone treatment in adolescents with gender dysphoria“, from the Journal of Clinical Endocrinology and Metabolism. The abstract is publicly available.

Blog reposted with permission.