Thyroid Disorders in Athletes

Abstract

When athletic performance begins to deteriorate, it is important to identify possible underlying etiologies to explain such a phenomenon. Causes include inadequate nutrition, improper training habits, infection, and hematologic or endocrine diseases. In athletes, a thorough investigation of potentially reversible underlying medical conditions may be warranted when there are noted disruptions in training, competition, and recovery. Thyroid disorders should be considered in athletes in whom such a condition is suspected. The clinical picture may not be entirely clear, as athletes may have serum laboratory values that do not accurately correlate with the presenting signs and symptoms, as one might expect. That picture is even further muddled in individuals undergoing significant physiologic stress, and in whom anabolic agents or exogenous thyroid hormone are used. Because there are currently no consensus guidelines on the matter, return to play issues must be addressed when implementing treatment strategies and monitoring serial laboratory values on a case-by-case basis.

Thyroid metabolism and supplementation: A review framed in sports environment

“…68 Nevertheless, in 2015, among other stakeholders, the United States Anti-Doping Agency (USADA) and United Kingdom Anti-Doping Agency (UKAD) petitioned WADA to include levothyroxine on the prohibited list, arguing that the medication is used for its performance-enhancing effects (USADA) and that the liberal prescription of this hormone is harmful to the health of athletes (UKAD). 67 Even so, WADA did not approve its inclusion, based on the lack of evidence of the influence of HT on athletic performance. 103,104 The arguments provided by USADA and UKAD, added to ethics issues and the apparent increase in TH use among athletes, should deserve updated attention.…”

“…Depletion of thyroid binding globulin (TBG) by anabolic steroid use reduces serum tT3 and tT4 levels, depending on the steroid's susceptibility to aromatization. 14,[65][66][67] A large number of compounds interfere, directly or indirectly, with the synthesis, release, or action of TH. Table 1 shows examples of compounds that influence the functioning of TH; some are included in the List of Prohibited Substances for athletes.…”

“…Depression following steroid withdrawal may cause decreased thyroid function. Depletion of thyroid binding globulin (TBG) by anabolic steroid use reduces serum tT3 and tT4 levels, depending on the steroid's susceptibility to aromatization 14,65–67 …”

“…After studying the effect of sport on thyroid hormones for years, Luksch and Collins 67 warned that athletes who present signs and symptoms of TH excess without previous history or physical examination findings that corroborate a true thyroid disorder could lead to the misinterpretation of a fictitious hyperthyroidism. One case of this type of clinical case misinterpretation was reported for a bodybuilder who was consuming T3 as part of dietary supplementation 96 …”

Quantification of thyroid hormones and analogs by liquid chromatography coupled to mass spectrometry. Preliminary results in athletes and non‐athletes serum samples

“…The T4 and T3 fractions not linked to serum proteins are those of clinical value, and for that reason, the measurement of those free fractions is a common practice in clinical and diagnostic laboratories. Total fractions are also measured to search for specific pathologies associated with thyroid function 13–15 …”