Standing just 3 feet 5 inches tall, Michael Reda was the shortest boy in his third-grade class last year.

But that was 15 months ago, before Michael began taking humatrope (search), a growth hormone designed to add inches to a person's height.

Since then, he's grown nine inches — quite a feat for a boy who previously had been growing only one inch per year.

Taking humatrope is not a new therapy. The hormone has been available for nearly two decades, and was first approved to treat children with growth-hormone deficiency.

A year and a half ago, the FDA approved humatrope to treat kids diagnosed with ideopathic short stature, or height deficiency with no specific cause.

Sales of the drug have spiked 15 percent since then, said Humatrope's manufacturer, drug company Eli Lilly (search).

But humatrope therapy for otherwise normal children like Michael Reda is controversial. It's sparked concerns that patients will use the hormone to increase height much the same way others use plastic surgery to alter nose or breast size, and raised questions about when medical science should leave Mother Nature alone.

"We are starting to ask medicine to solve what are essentially social problems, not medical problems," said Dr. Mark Kuczewski, a bioethicist at the Stritch School of Medicine (search) at Loyola University in Chicago. "That is, these children often don't have any underlying medical sickness or pathology."

"It really is a statistical thing," he added. "They are on one end of a bell-shaped curve in terms of stature and height."

Kuczewski said there's is no medical justification for hormone therapy in normal children who are just very short.

"We have seen steroids and hormones in high school athletes, and all of these kinds of things as people want to get bigger, faster and taller," he said. "We are living in the 'extreme makeover' society now, where we want medicine to make us more popular, make us more beautiful, make us live longer."

Supporters of humatrope treatments, however, disagree. They say that significant lack of height can lead to ridicule and low self-esteem, and burden children with a serious permanent social liability.

"If we can provide anything that's going to make him not stand out, then it's kind of our job to do that," said Michael's mother, Jennifer Reda. "Being short for a male is, unfortunately, not very accepted by society and I knew that it could cause him problems later."

She said the hormone therapy was not an attempt to fool Mother Nature, but instead to steer her back on course.

"[Michael's] genetic potential is really to be five-eight or five-nine, and so he wasn't going to reach his genetic potential," Reda said. "We weren't going to have a six-foot child, and we weren't trying to make him six-foot-four and a basketball player. We want him to reach his genetic potential based on my and my husband's height. And he wasn't going to do that without the growth hormone."

Dr. Fuad Ziai, director of pediatric endocrinology at Christ Medical Center (search) in Oak Lawn, Ill., said concerns that humatrope will be abused are largely unfounded.

Despite the FDA's expanded approval, he explained, the drug is still tightly regulated. It's not something that can be purchased at the corner drug store.

"The restrictions that are there have always been there," Ziai said. "You do not use growth hormone for normal people who are normal with their growth-hormone function and just want to be taller than what they are."

He cited cost as another barrier. The treatments can run to between $20,000-$40,000 annually.

Ziai does acknowledge, however, that ethical questions do arise in borderline cases where children are not severely short like Michael Reda, but are just under the normal height range.

"They just want to be a little taller, and you wonder whether you need to spend twenty to thirty thousand dollars a year," Ziai said. He also wondered if children should endure "the inconvenience of injections for an unnecessary treatment just to have them grow a few inches taller."

As with all drugs, Ziai said, there are always risks involved in hormone treatment.

"Like any other drug, when used appropriately, it does the magic," he said, "but if used inappropriately, of course, it's going to have some consequences."