OBJECTIVE: To characterize the 455-nm (yellow) absorbing pigments in human follicular fluid (FF). DESIGN: Serum and FF samples obtained from patients undergoing in vitro fertilization were analyzed for carotenoids, bilirubin, and beta-glucuronidase concentrations. Spectrophotometric analysis in the visible spectrum was performed on FF samples, and the delta OD455 absorbance was calculated. RESULTS: Thin-layer chromatography confirmed the presence of beta-carotene and bilirubin in FF. The mean (+/- SD) contribution of bilirubin and carotenoids to the FF delta OD455 absorbance was 64% +/- 9.6% and 22.7% +/- 12.1%, respectively. Bilirubin fractions in serum and FF samples were then compared. The median unconjugated bilirubin concentration in FF was lower than that in the serum (0.130 versus 0.288 mg/dL; P < 0.0001). The median conjugated bilirubin concentration was higher in the FF when compared with the serum (0.129 versus 0.101 mg/dL; P = 0.0018). beta-Glucuronidase levels in the FF were significantly lower when compared with serum concentrations. CONCLUSIONS: Bilirubin is the major contributor to the FF 455-nm spectrophotometric peak. The higher levels of conjugated bilirubin noted in the FF could in part be explained by the lower levels of beta-glucuronidase.
OBJECTIVE: To characterize the 455-nm (yellow) absorbing pigments in human follicular fluid (FF). DESIGN: Serum and FF samples obtained from patients undergoing in vitro fertilization were analyzed for carotenoids, bilirubin, and beta-glucuronidase concentrations. Spectrophotometric analysis in the visible spectrum was performed on FF samples, and the delta OD455 absorbance was calculated. RESULTS: Thin-layer chromatography confirmed the presence of beta-carotene and bilirubin in FF. The mean (+/- SD) contribution of bilirubin and carotenoids to the FF delta OD455 absorbance was 64% +/- 9.6% and 22.7% +/- 12.1%, respectively. Bilirubin fractions in serum and FF samples were then compared. The median unconjugated bilirubin concentration in FF was lower than that in the serum (0.130 versus 0.288 mg/dL; P < 0.0001). The median conjugated bilirubin concentration was higher in the FF when compared with the serum (0.129 versus 0.101 mg/dL; P = 0.0018). beta-Glucuronidase levels in the FF were significantly lower when compared with serum concentrations. CONCLUSIONS:Bilirubin is the major contributor to the FF 455-nm spectrophotometric peak. The higher levels of conjugated bilirubin noted in the FF could in part be explained by the lower levels of beta-glucuronidase.