Biology Running

Epidemic of Thin Hypothyroid People?

Professional runners are lean, but not usually mean. And while they may overtrain, which has a host of manifestations, they aren’t usually found to have overt hypothyroidism.

One endocrinologist in particular has apparently been diagnosing and treating many thin, lean, athletes with “subclinical hypothyroidism.” That is a real diagnosis, in which the TSH values are below what is generally considered abnormal. The estimates of the incidence of this condition range from 5%-10%.thyroid

So many things are altered by overtraining and by having a negative caloric balance in the case of withholding calories that one wonders if it is wise to give athletes synthetic thyroid hormane when they have a normal, but borderline TSH level. Could giving thyroxine lead to heart arrhythmia or decrease heat tolerance? Could it enhance performance although it isn’t on any prohibited list? The answers regarding performance enhancement seem to be both no and yes from the same sources. How common are TSH levels in the range of 2-5 mU/Liter among high level and hard training athletes? Does rest or an improved diet have an impact on these levels? All worthwhile questions which are not entirely answered.

The Wall Street Journal presents the side of the doctor who has diagnosed about 17% of the “Nike” athletes training with Salazar as having this condition. Carl Lewis was diagnosed with it before attempting to qualify for his fourth Olympics. The doc compares himself to “House” of TV fame as a mystery solver. I always considered House a sad story. He was addicted to Vicodan and usually needed at least five to seven attempts before he’d come up with the right diagnosis.

Flo Track presented a mature discussion on the topic with Lauren Fleshman saying that if only one doctor in the country was giving athletes the answer they wanted to hear, something just might be wrong with the picture.

I believe subclinical hypothyroidism exists. And I believe over training exists even more often. I’d recommend any athlete considering treating hypothyroidism while having a body fat of less than 12% should research the topic thoroughly and hope to soon find better statistics on training and endocrine hormone levels.

For all of us non-elite, non-professional athletes – make sure you pay attention to your body. Take the breaks you need, rest well, and eat well. And always avoid too much, too soon, too fast, too often, with too little rest. If you have signs of hypothyroidism, be sure to see your doctor.


The treatment of Subclinical Hypothyroidism Is Seldom Necessary. Chu, J and Crapo, L. Journal of Clinical Endocrinology & Metabolism. JCEM. October 2001,

Flo Track discussion on WSJ article and Subclinical Hypothyroidism

U.S. Track’s Unconventional Physician in Wall Street Journal

Subclinical Hypothyroidism: An Update for Primary Care Physicians Vahab Fatourechi, MD Mayo Clin Proc >v.84(1); Jan 2009 >PMC2664572


The Beatles “I’m Down” (Cause my thyroxine is low & my TSH is high?)