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Substantial advantage of a combined Bayesian and genotyping approach in testosterone doping tests.
- Source :
-
Steroids [Steroids] 2009 Mar; Vol. 74 (3), pp. 365-8. Date of Electronic Publication: 2008 Nov 13. - Publication Year :
- 2009
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Abstract
- Testosterone abuse is conventionally assessed by the urinary testosterone/epitestosterone (T/E) ratio, levels above 4.0 being considered suspicious. A deletion polymorphism in the gene coding for UGT2B17 is strongly associated with reduced testosterone glucuronide (TG) levels in urine. Many of the individuals devoid of the gene would not reach a T/E ratio of 4.0 after testosterone intake. Future test programs will most likely shift from population based- to individual-based T/E cut-off ratios using Bayesian inference. A longitudinal analysis is dependent on an individual's true negative baseline T/E ratio. The aim was to investigate whether it is possible to increase the sensitivity and specificity of the T/E test by addition of UGT2B17 genotype information in a Bayesian framework. A single intramuscular dose of 500mg testosterone enanthate was given to 55 healthy male volunteers with either two, one or no allele (ins/ins, ins/del or del/del) of the UGT2B17 gene. Urinary excretion of TG and the T/E ratio was measured during 15 days. The Bayesian analysis was conducted to calculate the individual T/E cut-off ratio. When adding the genotype information, the program returned lower individual cut-off ratios in all del/del subjects increasing the sensitivity of the test considerably. It will be difficult, if not impossible, to discriminate between a true negative baseline T/E value and a false negative one without knowledge of the UGT2B17 genotype. UGT2B17 genotype information is crucial, both to decide which initial cut-off ratio to use for an individual, and for increasing the sensitivity of the Bayesian analysis.
Details
- Language :
- English
- ISSN :
- 0039-128X
- Volume :
- 74
- Issue :
- 3
- Database :
- MEDLINE
- Journal :
- Steroids
- Publication Type :
- Academic Journal
- Accession number :
- 19056415
- Full Text :
- https://doi.org/10.1016/j.steroids.2008.11.003