Puberty blockers in Scotland: What are they and what does the evidence say?

The use of puberty blockers has been halted in Scotland – but what does the scientific and medical community say about their use?

Trans children in Scotland presenting at gender clinics will no longer be prescribed puberty blockers while health chiefs await the results of a study being conducted in England.

While children who are already being prescribed puberty blockers by one of Scotland’s two gender clinics will continue to receive the drugs, new prescriptions have been temporarily halted while further evidence is gathered.

What are puberty blockers?

While puberty blockers have been used to treat precocious puberty for decades, and gender dysphoria since the 1980s, there are still some risks

Puberty blockers are antagonists of gonadtrophin-releasing hormone, which controls the production of sex hormones such as testosterone, oestrogen and progesterone in the testes and ovaries.

Gonadotrophin-releasing hormone (GnRH) was first researched in the 1960s and 1970s, leading to Dr Andrew Schally and Dr Roger Guillemin sharing the 1977 Nobel Prize for determining the structure of the hormone.

According to Fertility & Sterility, an international scientific journal for doctors working in the field of reproduction, GnRH “serves as the conductor of the reproductive system, responsible for all its actions and, arguably, for life itself”.

Analogues of this hormone - artificially-produced GnRH - can be used to block male and female hormones from affecting the body.

Dr Hilary Cass speaking about the publication of The Cass Review. Dr Cass' report says said that gender medicine is “built on shaky foundations” and that children have been let down by a lack of research on the use of puberty blockers.

Synthetic GnRH, such as triptorelin, can be used in prostate cancer patients, for example, to block the secretion of testosterone, or in breast cancer patients to block progesterone and oestrogen.

As well as cancer treatment, these drugs are also approved for children with precocious puberty, a condition which causes children to begin puberty much earlier than normal. In girls, this is before they reach eight-years-old, and in boys it is before their ninth birthday.

Hormone therapies can halt precocious puberty, and allow children to come off the drugs and begin puberty at a normal age.

Many more children are prescribed puberty blockers for precocious puberty in Scotland than adolescents are for gender dysphoria. There is believed to be around 20 adolescents currently taking puberty blockers prescribed by gender clinics in Scotland, whereas precocious puberty affects around one in 5,000 children in the UK.

Why are puberty blockers given to trans children?

The idea is that adolescents who are experiencing gender dysphoria can effectively ‘pause’ developing into their body’s natural sex, allowing them to make a decision as to which gender they wish to progress into at a later age.

Puberty for young trans people can be a distressing experience - the discrepancy between their natural sex and the gender which they feel they belong to can cause psychological problems.

How are puberty blockers prescribed for gender dysphoria?

Children and young people experiencing gender dysphoria are referred to the Sandyford Clinic in Glasgow. After waiting for years, they then undergo several psychosocial assessments with various psychologists, who may have – before prescriptions were halted - decided to prescribe puberty blockers.

Currently, the Sandyford clinic is allocating appointments to young patients who were first referred to the service in June 2019.

They would then be referred to an endocrinologist, who would also have to agree that puberty blockers are the correct course of action. As such, between 2011 and 2023, only 87 young Scottish people were prescribed puberty blockers in Scotland for gender dysphoria.

What are the risks associated with puberty blockers?

While puberty blockers have been used to treat precocious puberty for decades, and gender dysphoria since the 1980s, there are still some risks, as with all medications.

According to the Cass Review, puberty blockers have “undergone extensive testing for use in precocious puberty and have met strict safety requirements to be approved for this condition”, however, the report highlights that their safety for use in treating precocious puberty is “a very different indication from use in gender dysphoria”.

The Cass Review makes a distinction between the treatment of precocious puberty in children and the blocking of puberty in adolescents, although it does acknowledge that “some endocrinologists have suggested that it is possible to extrapolate or generalise safety information from the use of puberty blockers in young children with precocious puberty to use in gender dysphoria”.

The report concludes there is limited long-term data available on the consequences of prescribing puberty blockers to young trans people, although there is a sizeable, well-established body of work outlining the safety of prescribing puberty blockers for precocious puberty.

One of the key concerns with puberty blockers is their effect on bone density, which multiple studies have found can decrease with use, although this could be mitigated with other medicines.

What are the psychological consequences of puberty blockers for trans children?

A 2021 UK-based study of early-intervention puberty blockers found that participant experience of treatment “was positive for the majority, particularly relating to feeling happier, feeling more comfortable, better relationships with family and peers and positive changes in gender role”.

In 2011, a Dutch study found that “behavioural and emotional problems and depressive symptoms decreased, while general functioning improved significantly during puberty suppression”.

However, the Cass Review reports that a study by the University of York concluded “there is insufficient and/or inconsistent evidence about the effects of puberty suppression on psychological or psychosocial health”.

What does the evidence say?

The problem is, as highlighted by the Cass Review, the pros and cons of prescribing puberty blockers for young trans people is not well-evidenced. This is largely due to a lack of a control group in previous studies, and the use of a placebo being unethical.

Furthermore, the reports says that “beliefs about their efficacy has arguably meant that other treatments (and medications) have not been studied/developed to support this group, doing the children and young people a further disservice”.

The vast majority of trans people who take puberty blockers then go on to take gender-affirming hormones, which further muddies the water when researching the outcomes of GnRH use.