CORTISOL CONCENTRATIONS IN POST COMPETITION HORSE URINE - A FRENCH AND BRITISH SURVEY

The purpose of the present report was to estimate the population param eters of cortisol concentrations in urine, an endogenous hormone used as a 'doping' agent and for which an international threshold (1.0 mu g /ml) has been proposed. Two data bases (French and UK) corresponding t o 112 and 142 samples, respectively were considered. Urine was collect ed under specific post competition conditions. Cortisol concentrations were obtained by validated methods (HPLC for the French samples, and GC-MS for UI( samples). No difference was observed between the 2 data sets and statistical analyses were carried out on the two merged files . The overall geometric mean cortisol concentration was 48 ng/ml. Dist ribution was not Gaussian. A log-normal distribution was not rejected (for P>0.05). Using the lognormal distribution, it was calculated that the probability of exceeding a cortisol concentration in urine of 1.0 mu g/ml was 1.1 x 10(-4). It was concluded that the actual internatio nal threshold is specific i.e. robust with regard to the risk of erron eously declaring an unmedicated horse as positive.