Australian children as young as three are now being referred for hormone treatment.

When Australian transgender trailblazer Georgie Stone first visited Melbourne's Royal Children's Hospital in 2007, she was the only patient that year to receive treatment for gender dysphoria.

But the world is changing, and it's changing fast.

Since 2012, the hospital's gender service has experienced an exponential increase in demand.

More than 230 referrals have been received this year, and more than 700 since 2003.

READ MORE:

* Serbian doctor tells of transgender reversals

* Becoming Sergeant Rhona: A transgender cop who has found acceptance in the force

* Kiwi retailers introduce transgender policies

* Meet Te Manahou MacKay, New Zealand's first transgender model

They include children as young as three, upset about being forced to wear certain clothes to kindergarten, and some teenagers who seek help alone because they are worried what their parents might think.

The hundreds of children seen at the hospital still likely only represent the tip of the iceberg, with one study estimating 1.2 per cent of adolescents identify as transgender.

More are coming forward as community awareness and acceptance of transgender people evolves, partly due to people such as Georgie, who helped successfully campaign to remove legal barriers for transgender children wanting to access hormone treatment.

Associate Professor Michelle Telfer, head of gender services at the children's hospital, said no gender service in the world was yet to see a plateauing of referral numbers.

"Nobody knows where that point may be," she said.

"These people have always been there across generations and across all cultures, but only now in the last five or 10 years it has become much more visible."

The continued growth in demand has recently been matched by new Australian guidelines for doctors treating transgender and gender diverse children and teens, developed by Professor Telfer and her team.

WITHHOLDING TREATMENT 'NOT A NEUTRAL OPTION'

The guidelines, described as the world's most comprehensive, recommend against genital surgery until a person reaches adulthood, but warns against unnecessary delays in other treatment such as drugs to prevent breast development in trans boys and voice deepening in trans girls.

Previously some guidelines have declared that no child should be given hormone treatment until they are aged 16. But Professor Telfer warned withholding treatment could prove extremely distressing for the child, and the right time to receive it was when the young person entered puberty, between the ages of 10 to 14 depending on the child.

Georgie became the youngest person in Australia to receive hormone blockers when she was 10 years and nine months old – and said she would have taken them earlier if she did not have to apply to the Family Court (a legal requirement recently overturned).

The guidelines also recommend fertility preservation be offered to children before they begin treatment. Georgie, for example, had a sample of testicular tissue taken and stored. It's hoped the tissue could be used to create a baby in the future, although the technology is yet to be developed.

Consent from parents or carers is recommended as ideal before a teenager begins taking oestrogen and testosterone, but may not always be possible – and the guidelines say bioethicists may be consulted for cases where parents do not approve with the treatment.

DOCTORS URGED TO USE CHILDREN'S PREFERRED NAMES

Younger children, meanwhile, will not require any drug or surgical treatment, and the guidelines instead focus on psychological support and helping a child with their social transition, which could include changing their name and hairstyle.

Georgie, who was just two when she first told her mum she "wanted a vagina", encouraged doctors to be mindful about using children's preferred names.

"When I was younger, it was not so widely considered how to handle pronouns," she said

"I remember I would be called out for a line as George or 'he'.

"That would really hurt me and I'd internalise it, but also people did not know any better."

Georgie will leave the care of the children's hospital when she turns 18 in May next year, and is set to undergo gender affirmation (reassignment) surgery in July.

The children's hospital says 96 per cent of the children it has diagnosed with gender dysphoria have continue to identify as transgender late into adolescence, and no patient who has started oestrogen or testosterone treatment has sought to transition back to their birth sex.