A novel high-throughput assay for the measurement of salivary progesterone by liquid chromatography tandem mass spectrometry

Background Liquid chromatography tandem mass spectrometry (LC-MS/MS) enables specific and sensitive quantification of steroids with a high throughput. Saliva sampling is advantageous for multisample profiling over longer periods of time, as it is non-invasive, cheap, can be carried out at home and does not require the attendance of clinical personnel. We developed a rapid LC-MS/MS for the measurement of salivary progesterone, frequently assessed as ovulation marker in patients desiring fertility. Methods Samples (300 mu L) were prepared by supported liquid extraction using dichloromethane and were reconstituted in 40% methanol. Chromatography was performed using a C8 column with a water/methanol gradient containing 0.1% formic acid and 2 mmol/L ammonium acetate. Quantification was performed with a Waters TQ-S mass spectrometer. Results Total run time was 5.5 min. The lower limit of quantification was 20 pmol/L (1.2 fmol on column). Inter- and intra-assay comparison showed coefficients of variation and bias between measured and nominal concentrations of less than 11%. Mean recovery was 91%. Interference with a large set of natural and synthetic steroids was excluded. The assay was successfully applied to measure progesterone variation during the menstrual cycle (n = 9) and diurnal variations during luteal phase (n = 7) in regularly cycling women. Discussion We present a novel LC-MS/MS assay for the determination of salivary progesterone with high-throughput potential. The applicability of the assay for progesterone profiling during the menstrual cycle is demonstrated.