Comparability of serum, plasma, and urinary estrogen and estrogen metabolite measurements by sex and menopausal status

Purpose The comparability between serum, plasma, and urinary measurements of estrogen metabolites via liquid chromatography–tandem mass spectrometry (LC–MS/MS) has not been largely explored, and it is unclear if urinary LC–MS/MS measurements are suitable surrogates of circulating levels. Methods Serum, plasma (EDTA and heparin), and urinary estrogen/estrogen metabolite levels were measured via LC–MS/MS in paired samples from 64 healthy volunteers (18 men, 20 premenopausal women, 26 postmenopausal women). Geometric means and Spearman correlation coefficients were used to compare individual and combined pathway levels of estrogens/estrogen metabolites across biologic matrices by sex/menopausal status. Results Measured concentrations of estrogens/estrogen metabolites across blood matrices were almost identical (percent differences