Are many star athletes secretly suffering from a thyroid condition that usually strikes post-menopausal women?

Last week, the Wall Street Journal profiled Jeffrey Brown, an endocrinologist to star athletes and a medical consultant for Nike. His roster of patients includes nine-time Olympic gold medalist Carl Lewis, and athletes treated by Brown have won 15 Olympic gold medals combined, according to the doctor.

“Among endocrinologists, Brown stands almost alone in believing that endurance athletics can induce early onset of a hormonal imbalance called hypothyroidism,” the Journal wrote.

Hypothyroidism is a condition where the thyroid -- a butterfly-shaped gland in the neck -- is underactive and doesn’t produce enough of some of the hormones a person needs to regulate their metabolism and other bodily functions. This hormonal imbalance can lead to a host of problems: heart disease, infertility, obesity and pain in the joints. It’s more commonly found in women over the age of 60, as well as in people that have had surgery on their thyroid gland.

Jeffrey Garber, the president of the American Association of Clinical Endocrinologists, says it’s hard to draw conclusions about Brown’s award-winning patients without knowing more details about their cases. But thyroid problems, he says, can be tricky things to pin down. Sometimes what seems like hypothyroidism actually isn’t.

For instance, “if you look at anorexics, their thyroid pattern can be confused with an underactive thyroid,” Garber said in a phone interview.

Falling levels of thyroid hormone aren’t always a bad thing. When people are starving, a drop in a thyroid hormone called T3 helps slow the breakdown of muscles; if T3 is artificially added, the muscle breakdown continues. Studies have shown that with certain injuries, like severe burns, high T3 levels are associated with worse outcomes, according to Garber.

In some cases, “it’s debatable whether the thyroid is underactive or whether it’s an adjustment of hormone economy,” Garber said.

It could be plausible that an overworked athlete’s body might be resisting muscle breakdown, resulting in what looks like hypothyroidism. Or perhaps there really are a lot of athletes unknowingly suffering from underactive glands, and the medical literature merely needs to catch up with reality.

“From a sports medicine standpoint, it’s not unusual in certain instances to look at these hormones,” Wake Forest Baptist Medical Center surgeon and sports medicine specialist Allston Stubbs said in a phone interview.

But the proliferation of hypothyroid diagnoses in the upper echelons of running, centered on the work of a single doctor, is raising eyebrows. Don Catlin, a doctor that opened the first lab in the U.S. aimed at looking for doping in sports, told the Journal that he suspected athletes were taking thyroid hormone for its stimulant effects.

Brown sticks to his guns and is acttively campaigning for endocrinologists to readjust their standards for thyroid hormone insufficiency.

"The general public seems to think that if you have a medical problem and then you get better, that you're on something [illegal]," he told the Journal.

Usually, hypothyroidism is treated with levothyroxine, a synthetic thyroid hormone. While thyroid hormones do stimulate the metabolism (along with the appetite, which is why Garber says they make “a terrible weight-loss drug”), they’re not currently banned by athletic authorities.

“Hypothyroidism treatment is not prohibited under the 2013 Prohibited Substances and Methods List as there is currently no evidence of performance enhancement,” World Anti-Doping Agency spokesperson Julie Masse wrote in an email.

There is a history of some athletes using thyroid medication for nonmedical purposes.

Heavyweight boxer Muhammad Ali was bested in 1981 by Jamaican boxer Trevor Berbick before a 10,000-person crowd in the Bahamas. Later, Ali blamed his poor showing on taking too many thyroid pills, which may have been part of an intense effort to make weight for the fight.

“I took too many thyroid pills,” Ali told the New York Times at the time. “Always used to double up on my vitamins. Bad idea with thyroid pills. Started training at 253, went down to 217 for the fight. Too much. People saying, 'Oooh, isn't he pretty?' But I was too weak, didn't feel like dancing. I was dazed. I was in a dream.”

Thyroid medication might also have some unintended effects that enhance performance, or at least make it appear that an athlete is taking performance enhancers.

In 2006, bicycle racer Floyd Landis blamed his hypothyroid medication for the illegally high testosterone levels detected in urine samples taken during his Tour de France ride, according to the New York Times. An overactive thyroid gland does seem to coincide with higher levels of testosterone, so it seems feasible that an increase in thyroid hormones from medication could cause a similar reaction. Race officials, however, were not swayed, and Landis was stripped of the yellow jersey that summer.