Could Performance-Enhancing Drugs Be Responsible for Small Pituitary Volume in Retired Boxers?

IN RESPONSE:

In our study, use of any kind of drug affecting the pituitary function was an exclusion criterion. None of the retired amateur boxers had a history of using any performance-enhancing drug, such as anabolic steroids or growth hormone, during their career. Although the use of doping agents, growth hormone in particular, is well known among professional athletes in Western countries (1), growth hormone vials were not available in Turkey, especially during the years of the retired boxers' active careers. Moreover, to avoid the use of doping agents, national and international amateur boxing federations have very strict regulations.

Although not enough data are available on the effects of long-term use of growth hormone on pituitary function and volume in athletes, one might expect the suppression of the growth hormone axis and decreased pituitary volume as suggested. However, after the cessation of growth hormone or anabolic steroids, the suppression of the relevant axis recovers over several months or rarely several years. The mean time since retirement was 16 years (range, 8 to 28 years) in our retired boxer group, enough time to recover from all possible drug-related changes.

In addition, there were significant negative correlations between the length of boxing career and growth hormone reserve. If retired boxers had used growth hormone, both growth hormone–deficient and growth hormone–normal boxers would be expected to have decreased pituitary volume. However, growth hormone–deficient retired boxers had significantly decreased pituitary volume when compared with growth hormone–normal retired boxers.

In a meta-analysis including the patients with head trauma–induced hypopituitarism due to various causes other than sports, growth hormone deficiency is the most common problem, and the rate of isolated hormone deficiencies is higher than the rate of multiple hormone deficiencies (2). Therefore, presence of the isolated hormone deficiencies, growth hormone deficiency in particular, was not surprising in our group of boxers. The anatomical localization of the growth hormone–secreting cells in the pituitary gland, which are located at the outer border and lateral wings, could be 1 possible explanation for the vulnerability of these cells to trauma. Moreover, in a very recent study, apolipoprotein E3/E3 genotype was shown to decrease the risk for trauma-induced hypopituitarism in boxers and kickboxers, suggesting a genetic susceptibility (3).

In conclusion, evidence shows that hypopituitarism in retired boxers is due to sports-related, long-term head trauma and could not be explained by possible use of doping agents. In addition, assuming a misuse of growth hormone by the boxers in our study (which is not the case) leads to overlooking the potential hazards of boxing on pituitary function. However, it would be interesting to investigate the pituitary consequences of long-term use of doping agents in professional athletes who had a clear history of using them.