MON-LB305 The “Normal” Hormonal Levels in Athletes: Should Reference Ranges Be Adapted for the Physically Active Population?

Abstract

Background:Despite the growing number of physically active subjects, including elite and amateur athletes, little is known regarding metabolic and hormonal chronic adaptations to exercises. While the elucidation of the hormonal and metabolic physiological adaptations to physical activity is of emerging importance, the Endocrine and Metabolic Responses on Overtraining Syndrome (EROS) study have serendipitously unveiled the existence of multiple metabolic and endocrine physiological changes in male athletes, including chronic increase of testosterone with concurrent physiological increase of estradiol, enhanced GH and cortisol responses to stimulations,andincreased catecholamines, basal metabolic rate, fat oxidation, and hydration status. These findings were uncovered due to a novel methodological design in which athletes affected by overtraining syndrome (OTS) were compared to a two control groups, of healthy athletes (ATL) and healthy non-physically active controls (NPAC). Since none of the parameters were directly dependent on exercise or performance, differences between these two groups were unexpected. From the fact that several parameters were shown to be different between ATL and NPAC, we realized that the use of the reference ranges for general population to analyze results in athletes may potentially under- and over-diagnose a wide range of conditions. Our objective is therefore to determine whether athletes should be biochemically evaluated through specific adapted ranges, and propose preliminary adaptations in these ranges. Methods: A systematic review on the literature on endocrine and metabolic adaptations to exercise was performed, as well as a thorough analysis of the seven arms of the Endocrine and Metabolic Responses on Overtraining Syndrome (EROS) study. Results:Multiple reference ranges were shown to be inaccurate for athletes. Among the parameters that should be adapted for athletes, and their respective adaptedranges include: 1. Cortisol response to an insulin stimulation test (ITT) (> 20.5 μg/dL); 2. GH response to an ITT (> 12 μg/L); 3. Prolactin response to an ITT (> 22 ng/mL); 4. Salivary cortisol at 8AM (> 450 ng/dL); 5. Total testosterone (> 450 ng/dL); 6. Estradiol (25-45 pg/mL) - and testosterone-to-estradiol ratio maintained > 13.7; 7. Total nocturnal urinary catecholamines (> 220 μg/12h); 8. Resting lactate (< 1.0 nMol/L); 9. Measured-to-predicted basal metabolic rate (BMR) (> 105%); 10. Fat oxidation (in relation to total BMR) (> 50%); and 11. Hydration status (body water > 62% of total body weight). Conclusion: Analysis of biochemical parameters in athleted should be interpreted with cautious, particularly hormonal and metabolic parameters, once many parameters likely undergo adaptive changes when under physical activity. Preliminary adaptations for the ranges have been proposed.