Urinary excretion of 19-norandrosterone of endogenous origin in man: quantitative analysis by gas chromatography-mass spectrometry.
A GC-MS method, using deuterium-labelled 19-noretiocholanolone as internal standard and following an extensive LC purification prior to selected ion monitoring of the bis(trimethylsilyl) ethers at ion masses m/z 405, 419, 420 and 421, allowed the quantitation of subnanogram amounts of 19-norandrosterone present in 10-ml urine samples at m/z 405. Thirty healthy men, free of anabolic androgen supply, delivered 24-h urine collections in 4 timed fractions. Accuracy was proven by the equation, relating added (0.05-1 ng/ml) to measured analyte, which had a slope not significantly different from 1. Precision (RSD) was 4% at a concentration of 0.4 ng/ml, and 14% at 0.04 ng/ml. Analytical recovery was 82%. The limit of quantitation was 0.02 ng/ml. The excretion ranges were 0.03-0.25 microg/24 h or 0.01-0.32 ng/ml in nonfractionated 24-h urine. Taking into account inter-individual variability and log-normal distribution, a threshold of 19-norandrosterone endogenous concentration of 2 ng/ml, calculated as the geometric mean plus 4 SD, was established. This value corresponds to the decision limit advised by sport authorities for declaring positive (anabolic) doping with nandrolone.
Laboratoire de la Fédération Nationale des Courses Françaises, Châtenay-Malabry, France.
L
L
Dehennin
Y
Y
Bonnaire
P
P
Plou
D000293:Adolescent; D000328:Adult; D002852:Chromatography, Ion Exchange; D002853:Chromatography, Liquid; D002940:Circadian Rhythm; D004300:Doping in Sports; D004962:Estranes / Q000652:urine*; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D015813:Substance Abuse Detection / Q000379:methods*
D004962:Estranes; C036015:19-norandrosterone