Steroid profile analysis and UGT2B17 genotyping of the same urine sample to determine testosterone abuse

Abstract

When testing a urine sample for testosterone abuse, a ratio of testosterone glucuronide (T) to epitestosterone glucuronide (ET) of 4.0 or above is considered suspicious. A degree of variation, however, has been observed in T/ET ratio between individuals from both the same and different ethnic backgrounds. The majority of this variation might be due to UGT2B17 deletion genotype (UGT2B17 deletion-type). The aim of this study was to investigate the use of the same urine sample for the analysis of T/ET ratio and UGT2B17 deletion-type. Japanese men were deletion-typed via a UGT2B17 copy number assay using DNA from blood. Urinary T and ET levels were determined using gas chromatography–mass spectrometry before (n = 112) and after a testosterone injection (n = 25). Basal T level and the increase in T/ET ratio after injection were dependent on UGT2B17 deletion-type, being lower in subjects with deletion (del/del) than nondeletion (ins/del or ins/ins) genotype. UGT2B17 deletion-typing was first performed using DNA from urine cryopreserved for 1–1.5 years (n = 66). The concentration of DNA required for discrimination between the deletion and nondeletion genotype by copy number assay was more than 0.1 ng/ml urine. Discrimination was possible in 94.0 % of urine samples (5–7 ml each). These findings show that T/ET ratio and UGT 2B17 deletion-type can be analyzed exclusively via urine samples, removing the need for the collection of other samples, such as blood or buccal cells. The combination of T/ET ratio and UGT 2B17 deletion-type may help inform decisions regarding a genotype-specific T/ET cutoff ratio.