“…Steroid metabolites were extracted from 50 μL of plasma using a solid-phase extraction method. 29 Briefly, each sample was mixed with 500 μL of methanol and 10 μL of the internal standard mixture ( Supplementary Table S2 ). The samples were mixed vigorously by vortexing for 1 min, followed by sonication for 5 min, and incubation on ice for 5 min.…”