Athletes and Thyroid Disease

What you're thyroid condition can mean for your performance on the field

Patient Expert

Thyroid disease doesn't discriminate. It affects both women and men. It affects people of all ages. And thyroid disease can strike whether you're a couch potato or an elite athlete.

When you’re an athlete, and your livelihood relies on peak physical and mental performance, what is the impact of a thyroid condition?

The thyroid and athletic performance

Thyroid conditions can affect both the physical and mental abilities of athletes.

Hypothyroidism — an underactive thyroid — can cause a variety of symptoms, including:

These symptoms are usually most severe in those who are undiagnosed, but they can persist even after treatment.

As you can see, hypothyroidism symptoms can be an impediment for athletes, who need energy, strong muscles, high levels of oxygen, and mental focus to perform their best.

Tennis star Jelena Dokic had to take a break from tennis to lose weight and regain her energy after her diagnosis of hypothyroidism. And no one knows the impact of thyroid-related weight gain better than Brazilian soccer star Cristiano Ronaldo, who received a great deal of public criticism and ridicule after he gained weight due to a hypothyroid condition.

Hyperthyroidism — an overactive thyroid — has equally debilitating effects on an athlete's ability to perform.

Hyperthyroidism can cause a variety of symptoms that affect athletic performance, including:

  • Insomnia, fatigue, and exhaustion
  • Rapid weight loss
  • Weakness of muscles, especially in the upper arms and legs
  • Loss of muscle mass
  • Anxiety, panic attacks, racing thoughts
  • Elevated heart rate, heart palpitations

Olympic runner Gail Devers’ athletic career was temporarily sidetracked when she lost significant amounts of weight, her hair fell out, and she was ultimately diagnosed with Graves’ disease and hyperthyroidism. Devers was treated, but it took two years for her to recuperate, regain her energy, and build herself back up enough to be in the physical and mental state to professionally compete again.

Famous athletes — Other famous athletes have been in the news for thyroid problems, including:

  • Golfers Ben Crenshaw, Ashara Munoz, Pat Bradley, and Rob Labritz
  • Soccer player Carla Overbeck
  • Skiers Nancy Greene Raine and Janica Kostelic
  • Tennis player Kiki Bertens
  • Hockey player Olli Maatta
  • Baseball player Daniel Norris
  • Basketball player and coach Coby Karl
  • Woman's basketball player Quynne Huggins

The thyroid “doping” controversy

Various organizations like the World Anti-Doping Agency (WADA) make rules about athletes’ use of performance-enhancing drugs. These groups have considered adding thyroid hormone replacement drugs like levothyroxine (Synthroid, Levoxyl, Tirosint) and liothyronine (Cytomel) to the list of banned substances.

The Wall Street Journal ran a highly-publicized story, titled “U.S. Track’s Unconventional Physician” that brought attention to the issue of thyroid drugs for athletes. The article focused on Dr. Jeffrey Brown, a physician who has diagnosed hypothyroidism in many track and field athletes. Two prominent runners he’s treated are Olympians Carl Lewis and Galen Rupp.

Dr. Brown believes that endurance sports may bring on hypothyroidism, and that hypothyroidism treatment gives his athletes an advantage over competitors who may have undiagnosed thyroid problems. According to Dr. Brown: “Undiagnosed athletes think if they work harder, the persistent fatigue and weakness will subside.”

Anecdotally, some endurance athletes report higher rates of hypothyroidism. Backing up Dr. Brown’s ideas, research has also shown that treating subclinical or borderline hypothyroidism can improve exercise performance and endurance.

It’s certainly possible that the great physical stress put on an athlete's body puts them at higher risk of hypothyroidism. And increased medical tests and greater scrutiny of hormonal issues in athletes may also be uncovering more undiagnosed thyroid issues. None of these issues have been studied at length, however.

A key point of controversy is that Dr. Brown and some other physicians diagnose and treat underactive thyroid conditions based on thyroid test levels that other endocrinologists consider normal and not requiring treatment. The liberal standards for diagnosis lead some physicians to question the validity of Dr. Brown’s ideas. Mayo Clinic endocrinologist Ian Hay, M.D., is quoted in the Wall Street Journal article, saying: “To see large numbers of young people, athletic ills being treated for thyroid deficiency would be considered unusual, if not a bit suspicious.”

The implication is that in some cases, hypothyroidism is being diagnosed, and medications prescribed to enhance performance, a process known as “doping.”

There are situations when athletes have misused thyroid hormone. Boxer Muhammed Ali, for example, reported using thyroid pills to lose weight before a 1981 fight. Dr. Brown, however, has pushed back against the idea that diagnosing and treating hypothyroidism constitutes doping, saying: “The general public seems to think that if you have a medical problem and then you get better, that you're on something illegal.”

The U.S. Anti-Doping Agency (USADA) and the United Kingdom Anti-Doping (UKAD) have been heavily pushing for a ban on thyroid hormone. After considering the issue, WADA again refused to include thyroid hormone on the banned list in 2016. According to WADA, the use of thyroid hormones by athletes is safe and does not provide a performance-enhancing advantage.

At this point, the controversy continues, and some questions still need to be answered:

  • Does endurance training increase the risk of hypothyroidism? Are athletes at higher risk of borderline or overt hypothyroidism?
  • Is there a valid reason to diagnose and treat hypothyroidism symptoms — even when blood test levels fall within the reference range — in athletes?
  • Do thyroid hormones enhance performance when given to an athlete who is not diagnosed with a thyroid dysfunction?
  • Should taking thyroid hormones in the absence of a thyroid diagnosis be considered “doping” in athletes?

What should you do?

If you are an athlete or you engage in endurance exercise or sports, it’s important to be aware of the symptoms of hypothyroidism and hyperthyroidism. If you have any signs of a thyroid condition, see your doctor for a comprehensive thyroid test panel and physical examination, and get treatment for hypothyroidism if warranted.

See more helpful articles:

You Might Be Hypothyroid If...

Is Your Thyroid in the Normal Range, But Not Optimal?

10 Warning Signs That Your Thyroid is Undertreated