As the combined enzymatic activity of CYP11A1 and SULT2B1 or CYP17A1 and SULT1E1 results in the production of PS and DHEAS, respectively, from cholesterol, the concentrations of these neurosteroids were determined in the peritoneal fluid of control and endometriosis patients, using liquid chromatography with tandem mass spectrometry (LC-MS/MS). Here, CYP11A1 is linked to endometriosis.