Determination of 17 alpha-hydroxypregnenolone in human plasma by routine isotope dilution mass spectrometry using benchtop gas chromatography-mass selective detection

A first assay based on stable isotope dilution/gas chromatography-mass spec trometry has been developed for plasma 17 alpha -hydroxypregnenolone, the l eading marker of 3 beta -hydroxysteroid dehydrogenase deficiency. Equilibra tion of plasma with internal standard was followed by solid phase extractio n. After clean up using Sephadex LH-20 mini columns, heptafluorobutyrates w ere prepared as derivatives. Quantification was achieved by selected ion mo nitoring of m/z 467.0 (analyte) and m/z 471.0 (internal standard). 0.030 pm ol of 17a-hydroxypregnenolone gave a signal to noise ratio of 3.7. Calibrat ion plot was linear. Spiking experiments showed good accuracy with relative errors < 3.7%. Intraassay precision CV was 8.3% and interassay precision C V was 5.6%. Requiring small amounts of plasma, the rapid, convenient work u p and the application of bench top GC/MS instrumentation proved our method suitable for routine clinical use in adults and children. (C) 2001 Elsevier Science Inc. All rights reserved.