Identification of Endogenous 19-Nortestosterone in Pregnant Ewes by Gas Chromatography–Mass Spectrometry

Abstract

Considered as a xenobiotic for many years, 19-nortestosterone has been extensively studied. Analyses developed to control the illegal use of this steroid in meat-producing animals led researchers to demonstrate the endogenous presence of 19-nortestosterone in several species. In this paper, the natural occurrence of 19-nortestosterone in its α form (epinandrolone) in the urine of pregnant sheep was demonstrated using gas chromatography–mass spectrometry. This reference method allowed 17α-nandrolone to be detected and identified, and the absence of the β epimer in the urine of pregnant sheep to be demonstrated. 17α-Nandrolone was accurately determined at different stages of pregnancy. The analyses showed that epinandrolone, which was not detectable in the urine of non-pregnant sheep, was excreted in small amounts (leading to a <0.5 ppb concentration) during the first 4 months of pregnancy. 17α-Nandrolone concentrations then increased during the last month until parturition. The origin of this molecule was not determined.