(Thyroid) Stimulating Conversation

So, two times in the last week, I've come across derivations of this article:

http://online.wsj.com/article/SB10001424127887323550604578412913149043072.html

which talks about a group of elite athletes who have all been diagnosed with hypothyroidism by one endocrinologist.  This article didn't say the doctor is giving these athletes legal performance enhancing drugs, but definitely alluded to the possibility. The article also states that something like 17% of Nike's elite running team has been diagnosed with hypothyroidism. Based on diagnosis rates within the general public, somewhere between 5% and 10% of Americans are thought to have hypothyroidism. A clear inference can be made! There are differences between these two populations, and perhaps even how careful they are with their health! Of course, I'm being somewhat tongue-in-cheek. Clearly, elite athletes and the general population have a number of different scales on which they are substantially different. Moreover, an elite athlete tends to be much more aware of his/her energy levels, overall health, and tends to be much more proactive about regular physicals and doctor visits. These two things in combination don't inherently suggest that the number of elite runners with hypothyroidism is inflated, but it does say there might be substantial bias in the sampling we have (most elite athletes would go to the doctor with chronic fatigue; most average people might not bother to have a test done at all).

I think it's somewhat dangerous to make inferences about a potential performance enhancement/detriment derived from a drug without formal, scientific, and statistically reasonable studies having been done on said drug. I'm hypothyroidic, as are a number of my non-athletic, young and relatively healthy friends. As the end of the article alludes, the medical community is divided as to (a) what constitutes too little or too much thyroid stimulating hormone, (b) how best to treat those conditions, and (c) what side effects (or intended effects) these treatments have.

It is certainly the case that levothyroxin is somewhat of a stimulant. But that's exactly the point: if you don't have enough of the natural stuff, your body has less natural stimulus than is considered "normal" or "healthy". Thus, the drug is intended to replace the stimulus your body isn't giving itself. The thyroid produces 2 versions of the same hormone, which affect metabolic rate, skin and hair health, digestion, energy levels, etc etc. I was tested and ultimately diagnosed with hypothyroidism not because of my running performance (I was diagnosed many years before I started competing again), or gaining weight (I'd been the same weight between 15 and 19, when I was diagnosed), but because my sleep patterns were super awry, pretty frequent nausea, and I had very dry skin.

The article mentions several athletes who have publicly announced their diagnosis with thyroid disorders, including Ryan Hall, Galen Rupp, Amy Yoder Begley, Bob Kennedy and Patrick Smyth. Individuals less familiar with hypothyroidism might immediately reach two conclusions: first, aren't those runners all really skinny for having hypothyroidism, and two, isn't it suspicious that those names include some of the fastest people in today's distance running scene?

As far as the first point, hypothyroidism has a number of symptoms, including but not limited to weight gain, chronic fatigue, sensitivity to heat and cold, trouble sleeping, skin and hair trouble, and digestive problems. The runners above all train for hours every day. It would not be surprising in the least if their training regiments mask the weight gain that might otherwise come from hypothyroidism. Moreover, even among more "average" people diagnosed with hypothyroidism, not everyone experiences weight gain as a symptom of the disease.

The second point leads me to a somewhat different set of questions. First, is there some reason that heavy training loads suppress thyroid function? Maybe that's why a bunch of serious athletes have been diagnosed. Second, as there is much dissent within the medical community about "normal" ranges of TSH, what sorts of ranges do the elite athletes who are being treated (by this doctor) have? Are they ranges that no one else in the country would call low? Or are they just on the high side of low? Do they exhibit symptoms of hypothyroidism, besides the normal fatigue plaguing other elite athletes under significant training duress? And finally, if an athlete has low iron counts (due, perhaps in part, to training), and takes iron to fix the problem, they will see an improvement in their performance. Does that make iron a performance-enhancing drug? 

Everyone agrees that some drugs are performance-enhancing, but what line must you cross? Healthy diet, too, can improve performance, though the food might not be in pill form. So might taking supplements for other deficiencies  or taking a daily multivitamin out of habit. So too might a male athlete getting testosterone injections. Where do we draw the line? Generally speaking, wherever that line is, most people would agree that food and multivitamins should not be considered performance enhancing drugs, and that EPO and HGH should. In between those two extremes, though, are a host of other "performance enhancers", that might improve the performance of some athletes, but are more or less "natural", and have smaller or larger natural levels within the human body.