A liquid chromatography–mass spectrometry method for the quantitative analysis of urinary endogenous estrogen metabolites

The ability to measure estrogen metabolites (EMs) quantitatively is important for investigating their individual roles in cancer screening, treatment and prevention, as well as in a host of other hormone-related disorders. In this protocol we describe a method that is capable of quantitating 15 distinct EMs in urine. Endogenous EMs are quantitatively measured using a liquid chromatography–tandem mass spectrometry method in which the spectrometer operates in a selected reaction monitoring mode. This method is capable of quantifying estrone and its 2-, and 4- and 16α-hydroxy and its 2-, 4-methoxy derivatives, and 2-hydroxyestrone-3-methyl ether; 17β-estradiol and its 2-hydroxy, and 2- and 4-methoxy derivates, and estriol, 16-epiestriol, 17-epiestriol, and 16-ketoestradiol. The method requires only 0.5 ml of urine and approximately 60 urine samples can be quantitatively analyzed per week.