title: Quantification of neurosteroids during pregnancy using selective ion monitoring mass spectrometry.
abstract: Analytical techniques used to quantify neurosteroids in biological samples are often compromised by non-specificity and limited dynamic range which can result in erroneous results. A relatively rapid and inexpensive gas chromatography-mass spectrometry (GC-MS) was developed to simultaneously measure nine neurosteroids, including allopregnanolone, estradiol, and progesterone, as well as 25-hydroxy-vitamin D3 in plasma samples collected from adult women subjects during and after pregnancy. Sample preparation involved solid-phase extraction and derivatization, followed by automated injection on a GC equipped with a mass selective detector (MSD) operated in single ion monitoring (SIM) mode to yield a run time of less than 11min. Method detection limits for all neurosteroids ranged from 30 to 200pg/mL (parts per trillion), with coefficients of variation that ranged from 3% to 5% based on intra-assay comparisons run in triplicate. Although concentrations of estradiol measured by chemiluminescent immunoassay (CIA) were consistent with values determined by GC-MS values, CIA yielded considerable higher values of progesterone, suggesting antibody cross reactions resulting from low specificity. Mean neurosteroid levels and representative time-course data demonstrate the ability of the method to quantify changes in multiple neurosteroids during pregnancy, including rapid declines in neurosteroid levels associated with delivery. This simplified GC-MS method holds particular promise for research and clinical laboratories that require simultaneous quantification of multiple neurosteroids, but lack the resources and expertise to support advanced liquid chromatography-tandem mass spectrometry facilities.
authors.affiliation: Department of Civil and Environmental Engineering, School of Engineering, Tufts University, 200 College Avenue, Medford, MA 02155, United States. Electronic address: kurt.pennell@tufts.edu.
authors.forename: Kurt D
authors.initials: KD
authors.lastname: Pennell
authors.affiliation: Department of Civil and Environmental Engineering, School of Engineering, Tufts University, 200 College Avenue, Medford, MA 02155, United States; Department of Public Health and Community Medicine, School of Medicine, Tufts University, 136 Harrison Avenue, Boston, MA 02111, United States.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Woodin
authors.affiliation: Division of Epilepsy, Department of Neurology, Division of Women's Health, Brigham and Women's Hospital, Harvard Medical School, 75 Francis Street, Boston, MA 02115, United States.
authors.forename: Page B
authors.initials: PB
authors.lastname: Pennell
mesh_terms: D000328:Adult; D001774:Blood Chemical Analysis / Q000191:economics / Q000379:methods*; D005260:Female; D006801:Humans; D013058:Mass Spectrometry / Q000191:economics / Q000379:methods*; D018377:Neurotransmitter Agents / Q000097:blood* / Q000302:isolation & purification; D011247:Pregnancy; D015203:Reproducibility of Results; D052616:Solid Phase Extraction; D013997:Time Factors
chemical_list: D018377:Neurotransmitter Agents
keywords: Gas chromatography; Mass spectrometry; Neurosteroids; Pregnancy; Quantification; Selective ion monitoring