Impact of the UGT2B17 polymorphism on the steroid profile. Results of a crossover clinical trial in athletes submitted to testosterone administration.

•This study presents results of a triple-blind randomized placebo-controlled crossover trial in healthy athletes with a single dose of 250 mg of testosterone cypionate, the aim was to evaluate the impact of the influence of the UGT2B17 gen on the urinary steroid profile.•The testosterone and several main metabolites excretion are clearly affected by the UGT2B17 gen, especially for homozygous mutant (del/del) group.•The measurement of LH, and the analysis of CIMRS are very useful for those cases when the T administration will be no detected.