Take five or 10 minutes, the professor said, and write down things that you love, like, need, or enjoy.

Now pair up with someone you don't know and spend 20 minutes introducing yourself. Talk about whatever you want. But don't mention anything that you wrote down.

Try going on for a half-hour without a word about the most important things in life. Imagine a full day.

"It might be difficult," said instructor Robin Brennan. "That's what this course is about. That is just a glimpse of what it is like for somebody who is LGBT" - lesbian, gay, bisexual, or transgender.

The course is about LGBT health disparities, many of which - such as higher-than-average rates of suicide, drug addiction, and smoking - are linked to greater stress. Fear of sharing personal information, even with a doctor, doesn't help.

The Drexel University School of Public Health this semester began what is believed to be the second program in the nation to offer a certificate in LGBT health.

The first, started in 2007 at the University of Pittsburgh, is taught on campus there. Drexel's certificate is granted only to online students, although it is expected to be available in the future to those who take the courses in physical classrooms.

At their first meeting on the Center City campus, some of Brennan's seven master's-level students were stumped by the opening question on a handout: What do you think caused your heterosexuality?

"I don't remember doing it," said LaurenOrsini.

Question No. 8 - Why do you flaunt your sexuality? Can't you just be who you are and keep it quiet? - got to Tosin Seriki: "Flaunt? I am who I am. Keep it quiet? No. That's me!"

Another exercise asked them to classify people as heterosexual, lesbian, gay, or bisexual based on brief descriptions, such as: A man who is more attracted to men than women, although all of his sexual relationships have been with women.

There was no correct answer, but the questions helped students dig into the meaning of "sexual orientation." (It is considered to be some combination of attraction, behavior, and identity. Transgender, on the other hand, the T in LGBT, is all about gender identity; a trans man or woman may be straight, gay, or bisexual.)

But labels oversimplify. More than 75 percent of lesbians have had a prior sexual experience with men, according to one study. And 9 percent of men who described themselves as straight in a 2006 New York City study said they had had sex with a man in the previous year.

That study also found something that doctors would want to know: Those 9 percent were less likely than other "straight" men to use a condom, raising their risk for HIV.

"Language is important," Brennan told her students, many of whom want to go into medical professions. Even a routine form that asks for "marital status" may suggest to a gay person that the doctor doesn't understand and may discourage the patient from revealing details about sexual orientation or gender identity.

Creating trust - by using the right language and asking the right questions - is essential to care, said Nurit Shein, executive director of the Mazzoni Center, whose primary-care clinic in Center City focuses on the LGBT community.

"If you are a new patient," she said, "a question would be: 'Are you sexually active?' And then, 'With whom are you sexually active? With men? With women? With both?' " Even if a young gay man "has not ever had sexual encounters, we would talk about HPV" - human papillomavirus - "and getting the Gardasil vaccine," which most doctors would offer only to girls.

Medical schools typically teach only a few hours about LGBT health over four years of training, said Randall Sell, an associate professor who created and directs Drexel's new program. He is hoping to educate health-care professionals and aspiring ones on the diverse needs of the LGBT community.

"For a handful of things, perhaps it doesn't matter," said Sell. "Like if you have a broken arm."

Some differences are due to access to care. Most health insurance, for example, is provided by employers. Women tend to work in jobs that are less likely to provide coverage. So a couple made up of two women is less likely to have insurance. Even if one woman does, most employers won't cover an unmarried partner.

Rates of anal cancer are higher for gay and bisexual men; breast and reproductive cancers are higher for lesbians and bisexual women.

Depression and anxiety are higher for all LGBT people, and they are far more likely to be victims of violence.

One estimate put the average age of death for transgender people at 39, Brennan said.

Still, there are almost no reliable statistics from large national studies - something that the programs at both Drexel and Pittsburgh aim to change.

"We have data going back more than 30 years showing gay men smoke more than heterosexual men, but we do not have a single study showing gay men have higher rates of cardiovascular diseases, emphysema, or lung cancer, and the reason we don't have the studies is that nobody studies sexual orientation in association with those kinds of outcomes," said Ron Stall, director of the Center for LGBT Health Research at Pitt's Graduate School of Public Health.

Without that data, there is less awareness of the issue and little reason to intervene.

Allison Baker is a second-year master's student at Drexel, a heterosexual woman who has always considered herself to be an ally of the LGBT community. Yet she had no idea before taking the class how sexual identity pervades every aspect of someone's life.

"I have always felt proud and comfortable talking about all components of my own identity - my vegetarianism, my atheism, my feminism, and my Pennsylvania Dutch heritage," she said. "If I had to hide any of those out of fears of being fired, ostracized, denied proper medical care, victimized, etc., as LGBT individuals sometimes have to do, that would have a profound effect on my well-being."

Even in the area that she wants to pursue after graduating - interventions to support long-term cancer survivors - she is realizing that it makes a difference.

"Some of the topics that come up in support groups," Baker said, "is how the cancer has affected romantic relationships and sexual health."

If LGBT cancer survivors don't feel comfortable talking about their lives in a support group, what kind of support can they get?