Establishing a ketoconazole suppression test for verifying testosterone administration in the doping control of athletes.

The ratio of urinary testosterone (u-T) to epitestosterone (T/EpiT) is used to disclose testosterone (T) administration in the doping control of sports, and a ratio greater than 6 constitutes an offence. Nevertheless, the possibility of biological outliers must not be discounted, and the use of ketoconazole has been suggested for a dynamic test to distinguish between such athletes and those using T. In this investigation, ketoconazole was administrated to three groups of T-pretreated and two groups of untreated healthy male subjects. The subjects in one of the pretreated groups were patients with mild hypogonadism. One untreated group consisted of athletes that had been tested three times with high urinary T/EpiT levels. The effects of ketoconazole administration on serum T (s-T) level and urinary T/EpiT ratio were monitored every 2 h for an 8-h period and clearly separated T-pretreated and untreated subjects into two clusters (P < 0.0001). The T/EpiT ratio increased and the s-T level remained unchanged in pretreated individuals during the ketoconazole test, whereas T/EpiT decreased by 60% and s-T by almost 90% in untreated subjects. The statistical power of the test increased by using several time points and combining the urinary T/EpiT with the s-T data. In conclusion, the ketoconazole test is suitable as a supportive dynamic test for the urinary T/EpiT ratio measurements in the doping control of athletes.