title: Unconjugated cortisol in human amniotic fluid: relationship to lecithin/sphingomyelin ratio.
abstract: A specific and thoroughly validated competitive protein binding radioassay has been developed for the measurement of unconjugated cortisol in human amniotic fluid. Cortisol levels rose throughout normal gestation from 8.6 +/- 0.8 ng/ml at less than 20 weeks to 19.8 +/- 1.5 ng/ml at 30-40 weeks. Levels were significantly higher in amniotic fluid samples having mature lecithin/sphingomyelin (L/S) ratios (greater than 2), and good correlation with individual cortisol values was obtained (r = 0.79; P less than 0.001). These results support the hypothesis that cortisol plays a role in fetal lung maturation.
mesh_terms: D000653:Amniotic Fluid / Q000032:analysis*; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis* / Q000502:physiology; D008168:Lung / Q000196:embryology; D010713:Phosphatidylcholines / Q000032:analysis*; D011247:Pregnancy; D011485:Protein Binding; D013109:Sphingomyelins / Q000032:analysis*
chemical_list: D010713:Phosphatidylcholines; D013109:Sphingomyelins; D006854:Hydrocortisone