Measurement of serum and peritoneal fluid LH concentrations as a diagnostic tool for human endometriosis

A rapid, sensitive enzymeimmunoassay for the measurement of LH concentratio ns in serum and peritoneal fluid samples of healthy women and women with en dometriosis is reported. The ligand (LH) was captured by a readily availabl e, widely used and well-characterized monoclonal antibody (mAb, 518B7) gene rated against the beta subunit of bovine LH. This mAb, although specific fo r LH, shows very little species specificity and detects LH by radioimmunoas say in humans. A polyclonal antiserum raised in rabbits against hCG was con jugated to horseradish peroxidase and was used as the second antibody signa l. This anti-hCG antiserum crossreacts with LH. The enzymeimmunoassay uses the standard human LH (hLH) preparations (NIADDK-hLH-I-3, AFP-827OB) and re sults are based on the relative concentrations of LH in serum and peritonea l fluid. Total assay time was < 3 h. The range of the standard curve was 0. 002-0.500 ng LH per well and the lowest concentration of hLH that could be distinguished from zero concentration was 0.15 +/- 0.02 ng ml(-1) serum and 0.058 +/- 0.021 ng ml(-1) peritoneal fluid. Clinical diagnostic parameters for the LH enzymeimmunoassay showed a sensitivity of 85.71%, specificity 9 2.50%, efficiency 88.54%, positive predictive value 94.11% and negative pre dictive value 82.22%. The study was retrospective. Serum LH concentrations of women with endometriosis were 13.67 +/- 7.21 ng ml(-1), whereas serum LH concentrations of women in the control group were 4.52 +/- 2.03 ng ml(-1). One-way ANOVA showed significant differences (P < 0.001) between women wit h endometriosis and control groups. Women in the control group had peritone al fluid LH values of 5.65 +/- 2.43 ng ml(-1), whereas peritoneal fluid LH values of 64.06 +/- 16.44 ng ml(-1) were obtained in women with endometrios is (P < 0.001). A cycle-dependent pattern of serum and peritoneal fluid LH concentration was observed in women in the control group, which was not obs erved in the peritoneal fluid of the group with endometriosis. The applicat ion of this assay to serum or peritoneal fluid samples provides the attract ive possibility that it could be included in the panel of markers used for diagnosis of endometriosis.