Hormone Therapy For Trans Teens
The remarkable deficiencies in new NHS policy looking at whether transgender teenagers should be able to access hormone therapy.
It’s been two years since the Cass review into gender identity services in the UK came out. Since then, the UK has progressively restricted access to gender clinics of all kinds for trans teens, now offering only a handful of appointments a year. The new clinics exclusively focus on psychological and psychosocial interventions, with the UK government having banned the use of puberty blockers entirely based largely on Cass’ recommendations.
The latest foray into removing access to medical interventions for transgender youth is the new NHS policy on hormone therapy. The draft policy proposition from NHS England states:
“NHS England has carefully considered the evidence reviews conducted by Solutions for Public Health (2026) and has identified and reviewed any further published evidence available to date. We have concluded that there is not enough evidence to support the safety or clinical effectiveness of feminising and masculinising medicines to make the treatment routinely available to children and young people at this time. This includes both individuals who identify with a binary, or a non-binary gender. “
This is based largely on a series of reviews conducted by Solutions for Public Health (SPH, an NHS evidence reviewing body), which are also linked in this policy proposal. The organisation has conducted a remarkable 10 systematic reviews and meta-analyses looking into a relatively simple question, and come to the conclusion that there is no good evidence that hormones are beneficial for transgender young people.
This is interesting, because the previous NHS-commissioned review, conducted by the University of York as part of the Cass review, found that there was “moderate quality” evidence suggesting a benefit for hormones. These new systematic reviews are, in theory, an update on that data, but somehow found substantially less evidence that hormones help transgender teens.
I was commissioned by Gender Plus, a private clinic for gender identity treatments in the UK, to look into these studies and provide a report on them. They are, in my opinion, largely useless as a guide for policy in the UK or anywhere else. They have serious weaknesses, and do not allow us to make useful decisions about, say, whether to ban hormones for transgender teens in the UK’s gender clinics.
Methodological Weaknesses
The first thing that I found in my report is that the reviews are quite weak from a methodological perspective. Specifically, they don’t report quite a lot of the important things that you’d expect systematic reviews to report. A systematic review is a way of aggregating all of the evidence together on a specific topic, and the methodology is therefore basically just how the authors identified studies and grouped them together. Usually, you report things like how you downloaded the studies, who did the extraction, and how exclusions were made.
These 10 reviews do not report any of those things. Instead, they refer to an internal NHS document called “Guidance on conducting evidence reviews for Specialised Services Commissioning Products’ (2020)”. There’s no information on what that document contains, and I could not find it online, which means that we simply do not know important things about these reviews.
For example, one common issue in systematic reviews is that it is not simple to decide whether a study meets or does not meet the inclusion criteria. It can be easy to miss specifics that might cause a study to be dropped from the analysis. That’s why we usually get two people to independently review the studies we’ve identified in our searches, and if they disagree on what gets included we have a third person on standby to be the deciding vote.
But in these SPH reviews, they don’t say that they did this. There’s just that reference to an internal document that may or may not include this important step. It’s possible the authors did do their reviews using standard methodology—it’s also possible that they did everything completely wrong. We just don’t know.
There are many basic measures of good systematic review practice that these SPH reviews don’t describe. That’s a serious deficiency, and makes it much harder to trust the results at the outset.
Excluding Most Evidence
The methodological weaknesses are bad, but much worse was the way the reviews put together their questions. The studies that they actually included. In all 10 reviews that they conducted looking at hormones for gender diverse teenagers, they included a total of just 11 studies. 6 of the reviews included no studies at all. In contrast, the York University review included 53 studies on the same broad question. How is this possible?
The issue comes down to the specific questions the SPH authors asked. A systematic review is fundamentally about finding the literature looking at a medical question. The method used by SPH to define these questions is called PICO—Population, Intervention, Comparator, Outcome. For example, we might want to know what impacts metformin, a diabetes medication, has on mental health compared to a placebo in people with pre-diabetes. That would be:
P: people with pre-diabetes
I: metformin therapy
C: placebo pills
O: mental health
There’s an important point here though. It is quite easy to make your PICO framework too broad—there are probably quite a few studies on the above question, making it a VERY tedious process to try and comb through them—but it’s also possible to make the PICO too narrow. If we changed the above PICO framework to something rather more specific:
P: women aged 40-55 with pre-diabetes and no history of mental health disorders who do not drink alcohol, take a statin, and exercise regularly
I: metformin taken twice a day
C: matched placebo pills taken in the same schedule as the metformin
O: a composite outcome including depression and anxiety scores
We would probably end up finding no studies at all looking at our new question. But the issue here is not that there is no research which might inform us, it’s that we’ve chosen a ridiculously narrow question to ask of the data. There are probably no randomized studies of metformin on this extremely specific population, but we have lots of randomized trials including many different groups that would almost certainly give us a strong answer as to what metformin would do in this situation.
In the SPH reviews, they made a simple mistake. Their questions were FAR too narrow. The example I picked in my report was review 2417k. This review had the PICO:
P: Children and young people (up to their 18th birthday) who have gender incongruence as defined by the study and identify as non-binary and wish partial physical masculinisation.
I: Masculinising medicines comprising testosterone monotherapy.
C: One or a combination of: 1. Psychological and psychosocial support 2. Social transitioning to the gender with which the individual identifies OR 3. No intervention
O: Impact on gender incongruence, Impact on mental health, Impact on Quality of Life, Masculinising physical changes, Psychosocial impact, Fertility, Feasibility of masculinising genital surgery, Cognitive outcomes, Detransition after receipt of masculinising medicines, Regret after receipt of masculinising medicines, Safety, Cost-effectiveness
This is patently absurd. For one thing, I have not been able to find anyone else who uses the phrase “partial physical masculinisation”. The concept of giving hormones to non-binary youth to cause partial changes in their gender expression is mostly theoretical at this point, and there are no studies looking at what this might mean in practice.
In addition, the ages are defined quite tightly. There’s little practical difference between hormone use for 17 year olds and 18 year olds, but the authors decided that they would exclude any study that looked at people over the age of 18 (this is also bad in another way—we’ll come back to that).
On top of all of this, they are only looking at “testosterone monotherapy”. That means that kids who ever got puberty blockers are excluded from this and all of the other SPH reviews that discussed monotherapy. The SPH team did run 4 reviews on combination therapy—hormones and puberty blockers—but they only included studies where the hormones and puberty blockers were provided concurrently for all patients in the paper.
This is ridiculous because any study where some portion of children got puberty blockers before hormones was automatically excluded from all the SPH reviews. That’s a large portion of the evidence-base on hormone use in trans teens. Worse still, it was standard NHS policy to require puberty blockers be given before hormones for children in the UK for nearly a decade, meaning that SPH automatically excluded all data from their own country as part of their review process. The reviews noted that “The generalisability of the findings to the UK is limited.”, but this was entirely due to the authors disregarding any UK evidence as a key part of their protocol.
It’s also problematic because most studies combine both gender transitions in their analyses. That is, they look at the impact of gender-affirming hormones for both young trans men and women at the same time. The biggest single cohort of trans youth taking gender-affirming hormones, for example, does not break out its analysis by gender, which means that it was excluded from all of the SPH reviews as well. One of the largest analyses of trans youth—which showed a reduction in suicidality for teenagers prescribed gender-affirming hormones compared to those who did not get hormones—was excluded because results were not published separately for those receiving testosterone vs oestrogen.
As I pointed out in my report, there are at least a dozen papers that show benefits for hormone use that SPH excluded in this manner. They defined their questions so narrowly that basically no studies could be included in the reviews, and then concluded that there was insufficient evidence to support the treatment. But the lack of evidence was just due to the mistakes in their own review process.
Inconsistencies
The final issue with the reviews that I discussed in my report was the inconsistency in how they applied their own inclusion criteria.
Remember the thing about age from above. Technically, the authors stated in their methodology that they would exclude any study that had people over the age of 18 in it. However, 7 of the 11 included studies had people >18 as part of the sample. What the SPH team appears to have done is decided that they could include studies with an average age <18. So a paper where the average age was 17.92, and which included a few dozen people over 18, would be included, but a paper where the average was 18.01 would not.
This is, obviously inconsistent. SPH was extremely rigorous with their application of the hormone prescription criteria. There were dozens of papers excluded because those papers had some teenagers in them who were given puberty blockers before hormones with no question about the average child.
But when it came to age, the reviews were much less stringent. There’s no information on how and why this choice was made.
Similarly, the reviews were divided into binary and non-binary groups. Every question was asked both for a binary physical transition—say, male to female—and for a non-binary physical transition (which was not defined by the SPH team). But there are virtually no studies that separate out their patients into those who wanted a binary and those who wanted a non-binary physical transition—they do occasionally just exclude non-binary people entirely—largely because the phrase “non-binary physical transition” appears to have been introduced by the SPH authors as part of these reviews.
The authors noted for all 11 of their included studies that they did not report whether these teenagers were given hormones for a binary or non-binary transition. But they still included them.
Had the SPH authors treated all of their PICOs as similarly important, they would’ve included no studies at all in any of their reviews. That’s rather problematic.
Should Teenagers Be Able To Access Hormones?
In my opinion, these SPH reviews are a total waste of time. You can’t possibly produce 10 reviews including just 11 studies and expect people to take the work seriously. The authors excluded most of the work looking at hormones for transgender teens, and ended up publishing what I would call completely useless systematic reviews.
They also excluded all evidence on simple, boring questions like whether hormones cause physical changes. This lead to the remarkable statement that the SPH team was unsure of whether giving children cross-gender hormones would cause changes to their bodies. Does giving testosterone to someone assigned female at birth change their body? How could we possibly know???
Which brings us to the real question: what does the data say?
We could go back to the York review, which found that there was some positive evidence showing that hormones improve the mental health of trans teens. We could also look at some of the data that’s come out since then, which also appears to be quite supportive of providing hormones to 16 and 17 year olds who want them. We could even read the only randomized trial of hormone therapy for transgender people, which was in young adults and found a fairly large benefit for mental health, and extrapolate to these older teens.
Unfortunately, the evidence is still just not that strong either way. As I’ve said many times before, I have no firm opinions on medication use for teenagers with gender dysphoria. The current best evidence is certainly supportive of hormone use for trans teens, but we still need better data before we can be really sure.
Regardless, what we can say with a great deal of certainty is that NHS England is currently relying on terrible evidence to make decisions about trans healthcare. It’s not just the SPH reviews—the NHS policy guidance document says:
“NHS England commissions the specialist NHS Children and Young People’s Gender Service. The service provides a focus on psychosocial, psychological and psychoeducational support following individual and family assessment.”
But their own evidence review—conducted as part of the Cass review—found that there was literally no evidence looking at these psychological, psychoeducational, or psychosocial interventions. Based on their own data, the NHS is implementing the treatment paradigm with the lowest quality evidence, all while publicly arguing that evidence is key.
I don’t know whether giving 16 year olds with gender dysphoria hormones is necessarily the best thing to do, but what I can say is that it has a lot more evidence behind it than the current NHS proposal.