δ13 C values of urinary 19-norandrosterone in antidoping samples and potential for adverse findings from boar offal consumption

19-Norandrosterone (19NA) is the preferred urinary target compound to identify doping with nandrolone or related 19-norsteroids. At concentrations between 2.5 and 15 ng/mL, isotope ratio mass spectrometry (IRMS) is required to establish exogenous origin of urinary 19NA. An absolute difference of 3‰ between urinary 19NA and an endogenous reference compound (ERC) constitutes a finding for exogenous origin of 19NA. Over the last 3 years, 77 samples containing urinary 19NA between 2.5 and 15 ng/mL were analyzed at our laboratory. The measured δ13 C values for 19NA ranged from -29.5‰ to -16.8‰. In comparison, the δ13 C values for the corresponding urinary ERCs ranged from -22.4‰ to -16.2‰. Due to the considerable overlap in values between the target compound and the natural range of urinary ERCs, it can be challenging to distinguish between endogenous and exogenous origins of urinary 19NA. In addition, it is well known that consumption of offal from non-castrated pigs can produce 19NA in urine. To determine whether this could cause a positive IRMS finding under the current IRMS positivity criteria, meat from non-castrated boars fed a mixture of corn and soy was consumed by 13 volunteers. Two volunteers produced 19NA findings above 2.5 ng/mL, and the measured isotope values, while inconsistent with documented 19-norsteroid preparations, did meet IRMS positivity criteria. However, these increases in 19NA urinary concentrations were short-lived due to rapid elimination. Timely follow-up collections may help support a claim for dietary exposure when low urinary concentrations of 19NA with pseudo-endogenous isotope values are observed.

Detecting the abuse of 19-norsteroids in doping controls: A new gas chromatography coupled to isotope ratio mass spectrometry method for the analysis of 19-norandrosterone and 19-noretiocholanolone

The detection of 19-norsteroids abuse in doping controls currently relies on the determination of 19-norandrosterone (19-NA) by gas chromatography-tandem mass spectrometry (GC-MS/MS). An additional confirmatory analysis by gas chromatography coupled to isotope ratio mass spectrometry (GC-C-IRMS) is performed on samples showing 19-NA concentrations between 2.5 and 15 ng/ml and not originated from pregnant female athletes or female treated with 19-norethisterone. 19-Noretiocholanolone (19-NE) is typically produced to a lesser extent as a secondary metabolite. The aim of this work was to improve the GC-C-IRMS confirmation procedure for the detection of 19-norsteroids misuse. Both 19-NA and 19-NE were analyzed as target compounds (TCs), whereas androsterone (A), pregnanediol (PD), and pregnanetriol (PT) were selected as endogenous reference compounds (ERCs). The method was validated and applied to urine samples collected by three male volunteers after the administration of nandrolone-based formulations. Before the instrumental analysis, urine samples (<25 ml) were hydrolyzed with β-glucuronidase from Escherichia coli and extracted with n-pentane. Compounds of interest were purified through a single (for PT) or double (for 19-NE, 19-NA, A, and PD) liquid chromatographic step, to reduce the background noise and eliminate interferences that could have affect the accuracy of δ¹³ C values. The limit of quantification (LOQ) of 2 ng/ml was ensured for both 19-NA and 19-NE. The 19-NE determination could be helpful in case of "unstable" urine samples, in late excretion phases or when coadministration with 5α-reductase inhibitors occur.

Application of online two-dimensional high-performance liquid chromatography as purification procedure to determine the origin of 19-norandrosterone in urine by gas chromatography-combustion-isotope ratio mass spectrometry

19-Norandrosterone (19-NA) is the main metabolite of nandrolone and/or its precursors, which can be found naturally in human urine in trace amount. Gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) confirmation procedure can be used to identify a potential exogenous origin of 19-NA in urine sample. Sample purification for GC-C-IRMS analysis is crucial to the whole confirmation procedure because the concentration of 19-NA in the urine to be tested is very low. Online two-dimensional high-performance liquid chromatography (2D-HPLC) clean-up procedure with high separation capacity is used to isolate and enrich 19-NA as a sample pretreatment process. Linearity, lowest detectable concentration, uncertainty, and selectivity of the method are validated according to the World Anti-doping Agency's (WADA) requirement. Isotope fractionation effect was not observed during the 2D-HPLC purification process. The validated method provides a high efficient and convenient confirmation procedure to determine the origin of 19-NA.

Pregnancy greatly affects the steroidal module of the Athlete Biological Passport

Concentrations of urinary steroids are measured in anti-doping test programs to detect doping with endogenous steroids. These concentrations are combined into ratios and followed over time in the steroidal module of the Athlete Biological Passport (ABP). The most important ratio in the ABP is the testosterone/epitestosterone (T/E) ratio but this ratio is subject to intra-individual variations, especially large in women, which complicates interpretation. In addition, there are other factors affecting T/E. Pregnancy, for example, is known to affect the urinary excretion rate of epitestosterone and hence the T/E ratio. However, the extent of this variation and how pregnancy affect other ratios has not been fully evaluated. Here we have studied the urinary steroid profile, including 19-norandrosterone (19-NA), in 67 pregnant women and compared to postpartum. Epitestosterone was higher and, consequently, the T/E and 5αAdiol/E ratios were lower in the pregnant women. Androsterone/etiocholanolone (A/Etio) and 5αAdiol/5βAdiol, on the other hand, were higher in the first trimester as compared to postpartum (p<0.0001 and p=0.0396, respectively). There was no difference in A/T during pregnancy or after. 19-NA was present in 90.5% of the urine samples collected from pregnant women. In this study, we have shown that the steroid profile of the ABP is affected by pregnancy, and hence can cause atypical passport findings. These atypical findings would lead to unnecessary confirmation procedures, if the patterns of pregnancy are not recognized by the ABP management units.

Implication of Human UGT2B7, 2B15, and 2B17 in 19-Norandrosterone Metabolism

Nandrolone (19-nortestosterone) is an anabolic androgenic steroid commonly abused for doping purposes. Nandrolone is mainly metabolized in the liver into 19-norandrosterone prior to glucuronidation and excretion through urine over an extended period of time. Several UGTs (i.e., UGT2B7, UGT2B15, and UGT2B17) are thought to be the major enzymes responsible for conjugation of androgens in human. An in vitro study using recombinant enzymes expressed in insect cells showed that UGT1A4 and UGT2B7 are the two main enzymes responsible of 19-norandrosterone glucuronidation. However, the identity of the enzyme involved in nandrolone metabolism in vivo together with their relative contribution and regulation remain unknown. Inhibition assays using human liver microsomes (HLM) incubated with 19-norandrosterone and selective inhibitors confirmed that UGT2B7 and UGT2B15 are involved in 19-norandrosterone glucuronidation, since the presence of the specific UGT2B7 and UGT2B15 inhibitors gemfibrozil and valproic acid inhibited the 19-norandrosterone glucuronidation by 35 and 45%, respectively. HLM were genotyped for UGT2B15 D85Y, UGT2B7 H268Y, and the UGT2B17 deletion polymorphism. The glucuronidation activity on 19-norandrosterone was significantly higher in UGT2B15 DD than in the other UGT2B15 genotypes (p < 0.05). Moreover, human liver cancer HepG2 cells were exposed to androgens to determine if the transcriptional activity of the genes of interest was affected. Only UGT2B7 mRNA expression was significantly increased (1.8-folds) after incubation with nandrolone decanoate. These results show that the UGT2B7 and UGT2B15 are involved in 19-norandrosterone glucuronidation and that the UGT2B15 polymorphism (D85Y) is the only UGT genetic variation that influences the glucuronidation activity. This could partly explain the inter-individual variation in 19-norandrosterone excretion.