Development and Validation of the Simultaneous Measurement of Estrone and 17β-Estradiol in Serum by LC-MS/MS for Clinical Laboratory Applications

A straightforward analytical method for the determination of estrone (E1) and 17β-estradiol (E2) at ultra-low levels in serum samples by LC-MS/MS has been developed and validated. This method entails an extraction and derivatization with dansyl chloride followed by separation with a C18 column. A comparison of the developed LC-MS/MS method against our routine immunoassay shows a good correlation for E2 while an important negative bias is observed for E1 by RIA. The later comparison for E1 shows the need to switch from the current routine automated immunoassays to highly-sensitive LC-MS/MS quantifications in order to provide accurate and reliable clinical results, especially at very low levels.