OBJECTIVE: To compare the precision of progesterone measurements obtained with the use of immunoassays and of liquid chromatography-tandem mass spectrometry (LC-MS/MS).DESIGN: Comparative study.SETTING: Academic, private practice, and in vitro fertilization (IVF) research centers.PATIENT(S): A total of 189 human serum samples were collected during controlled ovarian hyperstimulation and early pregnancy in women undergoing IVF.INTERVENTION(S): Serum progesterone pools (n = 10; 0.2-4 ng/mL) were sent to four laboratory centers that used four different automated immunoassay analyzers. Progesterone was measured by immunoassay in triplicate at three separate time points (n = 9 per pool) and by LC-MS/MS in triplicate once (n = 3 per pool).MAIN OUTCOME MEASURE(S): Inter- and intraassay coefficients of variation (CVs) of progesterone measurements were compared for each analyzer and LC-MS/MS.RESULT(S): Progesterone measurements by immunoassay were highly correlated with those by LC-MS/MS. Only two analyzers had intraassay CVs <10% at all three experimental time points, and only two analyzers had an interassay CV <10%. Mean progesterone levels by the analyzers were different across multiple progesterone pools.CONCLUSION(S): Our results indicate that progesterone threshold measurements used for IVF clinical decisions should be interpreted cautiously and based on laboratory- and method-specific data. A validated progesterone standard incorporated into daily immunoassays could improve medical decision accuracy.
Automation, Laboratory Biomarkers