Is thyroid replacement a performance-enhancing drug?

Has one physician uncovered the secret to Olympic Gold medals? And is that secret as simple as undiagnosed low thyroid function? That’s the question posed in a recent Wall Street Journal column entitled U.S. Track’s Unconventional Physician. Like the story that Steven Novella described yesterday, this narrative describes the medical practice of Dr. Jeffrey S. Brown, who sees thyroid illness where others see normal thyroid function. He has his critics, but his high-profile athlete patients have won a collective 15 Olympic gold medals. Case closed & Q.E.D.? Not quite. The WSJ actually does a pretty good job questioning the validity of Brown’s claims, which are far removed from the current medical consensus:

In athletic circles, Brown is a medical hero. He’s a paid medical consultant to Nike. The most renowned running coach at Nike, Alberto Salazar, calls Brown the best sports endocrinologist in the world. And athletes in growing numbers are coming to share Brown’s belief that heavy training can suppress the body’s production of the thyroid hormone, leaving them too exhausted to perform at peak. On the wall of the medical office of Jeffrey S. Brown is a photograph of Carl Lewis, the nine-time Olympic gold medalist. Lewis is one of several former or current patients of Brown’s who have climbed the Olympic podium, including Galen Rupp, who won a silver medal in the 10,000 meters at the London Olympics. “The patients I’ve treated have won 15 Olympic gold medals,” said Brown. Among endocrinologists, Brown stands almost alone in believing that endurance athletics can induce early onset of a hormonal imbalance called hypothyroidism, the condition with which he diagnosed Lewis and Rupp. Brown said he knows of no other endocrinologists treating athletes for hypothyroidism, a fatigue-causing condition that typically strikes women middle-aged or older. Several endocrinology leaders had never heard of hypothyroidism striking young athletes.

Now when I read “unconventional” and “stands alone” my skeptical alarm starts ringing. There is no shortage of debate about thyroid disease, ranging from the utter nonsense offered by “alternative health” practitioners to valid scientific discussions about the thresholds where normal function is considered abnormal and subject to treatment. Brown is an endocrinologist, however, and he’s treating elite athletes who are pushing their physical conditioning far beyond that seen by most medical doctors and almost all endocrinologists. So what’s the basis of the concern? The WSJ story goes on to discuss two different issues: What the proper threshold is for thyroid disease, and whether thyroid replacement is performance enhancing.  Let’s take each of these in turn. I’ve covered thyroid diseases and its related pseudoscience before, and a summary of the standard approach is necessary before we look at the some of the broader questions that have emerged from the story. All I know about these patients is what the WSJ is describing, so for the sake of brevity I’m going to focus on the types of cases that Dr. Brown appears to be identifying and ignore other causes of thyroid disease, which would require different treatment approaches.

The Diseased Thyroid
Simplistically, they thyroid gland acts as a sort of thermostat for the body. If it runs too high, you’re hyperthyroid: heat intolerant, anxious, a high heart rate, and maybe some diarrhea. If it runs low, you’re hypothyroid: cold, tired, constipated, and possibly even depressed. These multi-organ effects are triggered by the presence or absence of two thyroid hormones: thyroxine (T4) and liothyronine (T3). Normal thyroid function is something you never notice. But low thyroid function is common (4-10 % of adults), particularly in women. The overwhelming majority of cases (95%) of low thyroid, or hypothyroidism are primary, and the major cause of primary hypothyroidism (in parts of the world where we get adequate iodine) is autoimmune thyroid disease (Hashimoto thyroiditis). That is, the body attacks its own thyroid. As the thyroid’s function decreases, and T4 levels drop, the pituitary releases thyroid stimulating hormone – it’s effectively trying to “turn up the thermostat” to continue my analogy. A highly elevated TSH signifies thyroid dysfunction. There are other tests that can be done to confirm the diagnosis, including measurements of circulating T4 and antibody measurements, but TSH is the test we rely on as the primary diagnostic test.

Like any laboratory measurement, what’s considered a “normal” TSH is based in part on clinical studies, but also on the testing standard. Most labs identify an upper limit of TSH at 4 to 5 mU/L, but there are proponents of both higher and lower thresholds. Consequently there will be variations in practice between physicians in what they consider a “high” TSH and what’s considered “normal”. There is also some debate about a condition called “subclinical hypothyroidism”, where there are some laboratory signs of a thyroid dysfunction (a “normal” T4 and a slightly elevated TSH), but it’s not sufficient to warrant a diagnosis.  A Cochrane Review suggested that treating subclinical hypothyroidism doesn’t seem to result in meaningful differences in symptoms or quality of life, nor does it decrease cardiovascular morbidity. But neither did these studies look at the performance impact in elite athletes.

Not unexpectedly, Dr. Brown is a proponent of a using a low threshold to diagnose thyroid disease, setting a threshold that most endocrinologists consider normal:

According to American College of Endocrinology literature, the range of normal TSH level is broad, from 0.5 to an upper limit of near 5, depending on a patient’s gender, age and other factors. In practice, many endocrinologists consider TSH levels above 4—combined with symptoms such as fatigue—evidence of an underactive thyroid. Brown and a small camp of other endocrinologists argue that thyroid insufficiency can be signaled by a TSH level as low as 2, for which Brown cites some recently published research. By their standards, about 10% of the population is hypothyroid—double the 5% that is cited by mainstream endocrinology. Jeffrey Garber, American College of Endocrinology president, said hypothyroidism increasingly is being diagnosed in people who don’t have it, by endocrinologists whom Garber labeled as “alternative.” “The alternative crowd is saying, ‘Gee, this is why you’re not feeling better, because these [mainstream] doctors are clueless,’ ” Garber said. So if this reporting is accurate, Brown is looking at the same test results and seeing what he believes to be thyroid disease, where his peers see normal thyroid function.

Perhaps not surprisingly, Brown has his defenders, including bloggers who rail against “mainstream” endocrinologists who “stubbornly cling to the outdated ideas that hypothyroidism is easy to diagnose”. Sound like familiar rhetoric? It will if you’re a regular reader of this blog – every “maverick” physician will invariably have their defenders. But they’re usually not Olympic gold medalists:

Medical privacy rules forbid Brown from naming all the athletes he has treated for that condition. But among those who have publicly acknowledged being treated for thyroid problems by Brown or unnamed other physicians are American runners Ryan Hall, Galen Rupp, Amy Yoder Begley, Bob Kennedy and Patrick Smyth. “I knew hypothyroidism was kind of like something that was being diagnosed more among elite runners,” said Smyth, a marathoner who in 2011 started feeling chronically tired. When a physician near his California home found no evidence of thyroid dysfunction, Smyth flew to Houston to see Brown, who conducted some blood tests and diagnosed him with the condition. Smyth, now retired, said the medication never enhanced his performance.

The WSJ suggests that there may be some relationship between the rigorous training and the thyroid function itself, in which case the thyroid supplementation is simply restoring “normal” function. This seems to be what Brown believes, seeing dysfunction where other physicians see normal thyroid activity. Setting aside whether or not these athletes actually do have “low” thyroid, we can ask if thyroid treatment is actually offering a performance benefit when administered to patients with a TSH between what appears to be Brown’s cutoff of 2 and the standard cutoff of 4 or 5. Certainly Brown thinks so, or he wouldn’t be prescribing thyroid replacement. Given the extent to which these athletes push their bodies, even a subtle amount of fatigue, if ameliorated, could potentially improve performance. And overtraining leading to fatigue is likely a risk for athletes training at this intensity. From this perspective, it raises the question of whether thyroid replacement can be considered a form of doping – a recovery-enhancement or fatigue-deferring boost not available to athletes who didn’t go see Dr. Brown. T4 is a hormone, after all, and it will have effects on fatigue and recovery from exercise.

One of the differences that thyroid replacement has from other forms of sports supplementation is that there is a clear peak point – normal thyroid function. Thyroid replacement in the absence of real deficiency could create a hyperthyroid state which would possibly hurt athletic performance as much a hypothyroidism. Overt hyperthyroidism causes anxiety, insomnia, weakness, perspiration, and mood swings – nothing an athlete wants. Even subtle hyperthyroidism could have negative effects for elite athletes. And the long-term consequences are significant. Thyroid replacement is a life-long commitment. And long-term it has side effects including cardiovascular and bone risks – excess thyroid is a definite “bone eater”, with bone resorption stimulated and osteoporosis being the result.

The Wall Street Journal‘s profile of Dr. Brown and his unorthodox management of elite athletes raises interesting questions about the basis of disease, the conditions for drug treatment, and the implications on the ethics of sports.  Over time, thyroid replacement could go one of two ways. It could continue to be treated like inhaled anti-asthma medications, where asthmatic athletes who require treatment would otherwise be at a serious disadvantage in athletic competitions. We’d consider this simply a leveling of the playing field for those athletes. Or it could be that thyroid replacement could be scrutinized even more closely, perhaps requiring better documentation to justify use in an athlete, requiring clearly-demonstrated medical need based on a specific set of parameters, recognizing that there’s thyroid replacement, and then there’s unnecessary supplementation. From my personal perspective, I’m skeptical of medical mavericks who haven’t yet produced enough evidence to convince their peers and change the medical consensus. Until I see the evidence, I’m staying skeptical of Dr. Brown’s approach.

Posted in: Medical Ethics, Science and Medicine

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