YOUNG people from the age of 12 who feel trapped in the body of the wrong sex can now receive hormone-blocking drugs to halt puberty in a pioneering north London study.

The treatment is prescribed for people diagnosed with Gender Identity Disorder (GID) – a rare psychiatric condition where a person is born one sex, but feels they are the opposite sex.

One of the main effects of the drugs is to stunt the development of sexual organs so less surgery will be required if someone chooses to permanently change their gender at a later date.

However, bodily and hormonal changes will continue as normal if the medication is stopped.

Until this month, British doctors were prevented from offering youngsters diagnosed with gender issues any medical intervention before the late stages of puberty.

But now the National Research Ethics Service has given approval to the UK’s only specialist clinic for GID – at the Tavistock and Portman NHS Trust in Belsize Park – to prescribe the drugs to youngsters from 12 years old.

Clinic director Dr Polly Carmichael says the reduction in the age limit will be welcomed by families who would have otherwise had to travel abroad to the US for the treatment.

She said: “The majority of our referrals are 15-plus and we get fewer from a younger age group.

“Certainly, of the children between 12 and 14, there’s a number who are keen to take part. I know what’s been very hard for their families is knowing that there’s something available but it’s not available here.”

The hormone blockers will only be given to children and teenagers selected for an NHS research project jointly run by the Tavistock and University College London Hospital.

To take part, they will have to meet strict eligibility criteria.

These will include having full support from their parents, the existence of long-standing gender identity issues, an ability by the child to give formal consent and an absence of other mental health problems.

Those chosen will go through a series of psychological and medical assessments before receiving the blockers in injection form every 28 days or 10 weeks.

As a result, they will stop producing the hormones which tell the sex glands to make oestrogen or testosterone.

Boys will be prevented from developing male traits such as facial hair, deeper voices and Adam’s apples and girls will not develop breasts or menstruate.

But Dr Carmichael stressed that the majority of younger children diagnosed with GID do not actually go on to have sex changes and are simply gay in later life.

In these cases, their families receive help in the form of psychological rather than medical interventions.

The Tavistock and Portman clinic is currently the only place in Britain where under-18s with GID – some as young as three – and their relatives can access specialist psychotherapy.

The 22-year-old service, which received 127 referrals this year, helps families avoid common traps such the temptation to keep their child’s condition secret.

And it advises them on how strike a balance between recognising and accepting their child’s gender issues and being realistic about society’s prejudices.

Illustrating the dilemmas families go through, Dr Carmichael recalled one mother who was at a loss when her seven-year-old son began begging for a pink coat for school.

“They were out buying new clothes to go back to school and one brother was choosing a boyish coat while the other boy was gravitating to a pink fluffy coat,” she said.

“The mother was torn between on one hand allowing her child to express his wishes, while on the other wanting to protect him from ridicule from students if he did have the pink coat.”

Dr Carmichael said her team also offered emotional and psychological therapies to families struggling to cope with GID.

“The young person can suffer feelings of isolation and depression, while their parents often experience feelings of mourning for the child they gave birth to,” she explained.

Many families seek additional assistance from a support group called Mermaids, which has seen a 10-fold increase in its inquiries since it was set up by a set of parents in 1995.

For more information about this organisation, visit www.mermaids uk.org.uk.