Teens today are "trying out being transgender" to appear "different" to their peers or to gain attention, a leading gender expert has suggested.

Psychiatrist Dr Stephen Stathis, who runs a gender clinic, Brisbane's Lady Cilento Children's Hospital, told the Courier Mail he had seen a lot of adolescents "trying out being transgender" to stand out.

"One said to me, 'Dr Steve ... I want to be transgender, it's the new black'," he said.

Stathis added that a gender dysphoria diagnosis will be given to only a small percentage of the 180 minors who seek treatment at his clinic this year. Gender dysphoria is defined as a "strong, persistent feeling of identification with the opposite gender and discomfort with one's own assigned gender," and a diagnosis of the disorder is the first step for a transgender person to begin transitioning.

In an earlier interview last month, Stathis said that a majority of the patients he sees who "present with gender variant interests and behaviors, or are gender diverse" don't need treatment, as most identify as their birth gender by the time they reach puberty. 

"You might get a six- or seven-year-old girl wanting to dress as a boy," he said. "She may even say she wants to be a boy. When she hits puberty, she says, 'No, I'm just a girl who likes to do boy things."

He added, "Numbers of young people were getting their sexual identity mixed up with their gender identity...There's so many different terms, gender diverse - their interests and behaviors were not falling between what we would call cultural norms."

Girls, Stathis said, could do "stereotypical boys things" and simply be called a tomboy. "But boys, you put on a pink tutu and you're off to see the doctor," he said. "There's a lot of cultural norms here which makes it very complex."

Stathis said that before he'll prescribe hormone blockers to minors, he requires them to undergo intensive mental-health screenings with multiple psychiatrists.

Transgender children and teens have been the focus of considerable media attention in recent years and have seen an increased visibility in film and television. Last year, transgender teenager Jazz Jennings starred in Microsoft's Christmas-themed ad, and National Geographic featured a 9-year-old transgender child on the cover of its January issue.

At the time, The American Family Association described the promotion of gender dysphoria as "shaking a fist at God."

"BE WARNED PARENTS AND GRANDPARENTS!!! National Geographic shakes a fist at God and biblical authority on their radical mission to advocate gender confusion in upcoming issues. The biblical teaching of the truth about gender identity is confirmed by biological science," the group said on its Facebook page.

"Human sexuality is binary by design. Binary means there are two and only two options according to medical science - a child either has an XY chromosomal pattern or an XX. These are genetic markers which indicate God's master design for humanity and create the capacity for human reproduction," it added. "This Scripture verse comes to mind, 'But if you cause one of these little ones who trusts in me to fall into sin, it would be better for you to have a large millstone tied around your neck and be drowned in the depths of the sea.' Matthew 8:16 NIV."

Pope Francis has also spoken out against teaching gender theory to children, calling it "indoctrination." Gender theory is the idea that while people may be biologically male or female, they have the right to identify themselves as male, female, both or neither.

In October, he told reporters that gender theory being taught in schools "is against natural things."

"It is one thing for a person to have this tendency, this option, and even change sex," he said. "But it is another thing to teach it, gender theory, in schools along these lines in order to change mentality. I call this ideological colonization."