Wellington High School is one of several schools nationwide that have developed gender neutral bathrooms for the growing number of gender diverse pupils.

A tsunami of transgender young people is poised to swamp New Zealand's ad hoc transgender health services, experts say.

Increasing social acceptance of gender diversity, combined with the availability of puberty-blocking drugs, means more young people are coming out as transgender, and at an earlier age.

New figures obtained by Stuff show the number of 10 to 14-year-olds taking puberty-delaying Leuprorelin has soared from 27 in 2005 to 95 last year.

Counsellor Mani Mitchell said the surge was reminiscent of growth in the gay community in the 1950s and 60s.

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"We basically have a tsunami at the moment and we're not ready. We don't have enough people trained. It isn't funded adequately."

Transitioning from male to female, or female to male, was complicated and difficult in New Zealand, Mitchell said. Services were ad hoc and no surgery was publicly funded.

A New Zealand Medical Journal paper in May found inconsistencies and "significant barriers to care in many regions". Before prescribing hormones, some endocrinologists required a psychological assessment, which was rarely publicly funded.

Rachel Johnson, adolescent physician at Auckland's Centre for Youth Health, had only a handful of young transgender patients when she started in 2008. Now she treats about 100, mostly aged 12 to 24. Boys identifying as girls were most common but that was slowly changing, she said.

Teens can take hormones to mimic the puberty transformations of their desired sex. However, that is restricted to over-16s, because of irreversible potential side effects, including infertility. The availability of puberty-blocking drugs had been a huge change, as they bought time, enabling young people to start transitioning earlier, Johnson said.

While family acceptance was the biggest barrier for transgender young people, the lack of publicly funded surgery was worrying, she said.

An Auckland sexual health service doctor of 25 years, Rick Franklin, said greater acceptance and awareness of gender diversity was unmasking previously hidden health needs.

While the four northern region DHBs had funded a plan for an improved, combined service, transgender patients outside main centres were being left in the cold, he said.

"It grinds incredibly slowly for those of us who work at the coalface, where we need these services now or yesterday, not in six months' or 12 months' time."

Health Ministry acting chief medical officer Andrew Simpson said there were 71 people waiting for male to female surgery and 17 waiting for female to male reassignment.

The ministry has funding for three male to female operations and one female to male operations every two years, through its High Cost Treatment Pool. However, no new surgery has been funded since 2013.

Simpson said four male to female and one female to male operations were expected to be completed overseas next year. There would also be "catch-up" surgery once the new system was bedded in, he said.

Mani Mitchell also advocated public funding for chest surgery, which could revolutionise the lives of previously depressed and anxious transgender people.

"It's like a literal light switch has gone on. A different person walks in through the door."

HOW YOUNG IS TOO YOUNG?

Many children experience discomfort with their gender, but only about one-fifth grow up to be transgender adults.

Rachel Johnson, adolescent physician at Auckland's Centre for Youth Health, warned against medicalising gender confusion pre-puberty, such as boys who fancied high heels or girls who liked dump trucks.

However, if gender issues caused serious distress, the child could be supported to live as the opposite gender, Johnson said.

"Usually the child will lead this. If the child is so distressed that they can't go to school or they'll come home in tears. Most of those kids come to the clinic and they've already transitioned. For the families it was a no-brainer because their child was so upset."

FOR MORE INFORMATION

A Guide for Parents - If you are concerned about your child's gender behaviors