Intérêts du Dosage du Cortisol Plasmatique Chez Des Cyclistes Élite

In 2003, basal plasma cortisol was performed on 1 549 serum samples. It concerned 482 elite cyclists (67 women and 415 men) ageing from 25.5 +/- 4,8 years. Six (0.4%) and 352 (22.4%) cortisol were respectively under and above of the reference range values. The mean of cyclists' basal plasma cortisol - 507 +/- 210 nmol/l (range 30 - 4 745) - was higher than those expected in a non sportsmen population. The mean of basal plasma cortisol was also influenced by the period of intense cycling practice and the category, since it was higher in spring and summer than in autumn (p < 0.001) and in professionals than in amateurs (p < 0.001). Surprisingly, cyclists who declared corticosteroid therapy (n = 102) did not have a lower plasma basal cortisol than cyclists not treated (n = 380) (t = 1.22; p = 0.223). Our study have shown that intensive practice of cycling increases plasma basal cortisol. The physiopathologic meanings are discussed. Lower values evoke a corticosteroid-induced hypopituitary adrenal axis freination and an adrenal insufficiency must be sought. Higher values could be iatrogenic (increased cortisol binding globulin, cross-reaction with synthetic corticosteroids or corticotrophins abuse) or related to intensive practice. Nevertheless, a high basal plasma cortisol is not equivalent to an increased daily cortisol secretion and complementary investigations are useful to rule out a hypercorticism.