Effectof Albuminand Lamellar Bodieson FluorescencePolarizationof AmnioticFluid

Using a probe and procedure developed for the Abbott TOx analyzer, we investigated the influence of albumin on fluorescence polarization of amniotic fluid. Polarization readings increased when albumin was added to either “mature” or “immature”amnioticfluids. Albumin added to a fraction rich in lamellar bodies (10 000 x g pellet) greatly increased polarization readings, but albumin added to the lamellarbody-free fraction resulted in only small increases. Adding increasing amounts of the lamellar-body-rich fraction from mature and immature pools to a constant amount of albumin decreased the polarization readings. We saw no correlation between amniotic fluid polarization and albumin concentration but found a significant correlation between polarization values and either total extractable phospholipids (r = 0.725, P <0.001) or the ratio albumin/total extractable phospholipids (r = 0.784, p <0.001). The concentration of albumin in amniotic fluid was variable and correlated poorly with gestational age.