BACKGROUND Eurycoma longifolia Jack (ElJ) has been shown to elevate serum testosterone and increased muscle strength in humans. This study investigated the effects of Physta(®) a standardized water extract of ElJ (400 mg/day for 6 weeks) on testosterone: epitestosterone (T:E) ratio, liver and renal functions in male recreational athletes. METHODS A total of 13 healthy male recreational athlet...

BACKGROUND Carbon isotope ratio methods are used in doping control to determine whether urinary steroids are endogenous or pharmaceutical. METHODS Gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) was used to determine the delta(13)C values for 5 beta-androstane-3 alpha,17 beta-diyl diacetate (5 beta A), 5 alpha-androstane-3 alpha,17 beta-diyl diacetate (5 alpha A), an...

The measurement of the testosterone to epitestosterone ratio (T/E ratio) in urine is often used as a marker for testosterone administration in the doping control field. This study examines the frequencies of the different expression forms of the UGT2B17 gene, and assesses their effects on this marker in volunteer subjects. The sample for this descriptive study was composed of male and female at...

CONTEXT Testosterone abuse is conventionally assessed by the urinary testosterone/epitestosterone (T/E) ratio, levels above 4.0 being considered suspicious. The large variation in testosterone glucuronide (TG) excretion and its strong association with a deletion polymorphism in the uridine diphospho-glucuronosyl transferase (UGT) 2B17 gene challenge the accuracy of the T/E ratio test. OBJECTI...

Steroid profiling was introduced to determine the endogenous steroid misuse in sports. Thus, screening for the exogenous use of these prohibited substances can be established by monitoring a range of endogenous steroids, which constitute the steroid profile and evaluate their concentrations and ratios against reference values. The steroid profiling is currently based on population statistics. A...

CONTEXT The conspicuous interindividual differences in metabolism and urinary excretion of testosterone and its metabolites make it challenging to reveal testosterone doping. The variation in testosterone glucuronide excretion is strongly associated with a deletion polymorphism in the uridine diphosphate-glucuronosyltranferase (UGT) 2B17 gene. OBJECTIVE The objective of the study was to ident...