title: Direct radioimmunoassay for serum estriol during pregnancy.
abstract: I describe an assay for serum estriol during pregnancy, which does not require prior extraction or chromatography of the serum. Fifty microliters of 20-fold diluted serum can be assayed to detect as little as 20 pg of estriol. For a 20 mug/liter serum estriol concentration the CV was 16%; for 100 mug/liter concentration it was 5%. There was no significant interference by serum "binding" proteins. The assay measures unconjugated estriol, estriol conjugated with either sulfate or glucuronide at the 3' position, and a portion of the estriol 16 alpha (beta-D-glucuronide). Serum estriol concentrations increase during gestation from a low at 20 weeks of less than 10 mug/liter to a high of 100-150 mug/liter at term. Serum estriol values correlate well with those for urinary total estrogens and with values for human placental lactogen in serum at various gestational ages.
mesh_terms: D004964:Estriol / Q000097:blood*; D004967:Estrogens / Q000652:urine; D004966:Estrogens, Conjugated (USP) / Q000097:blood; D005069:Evaluation Studies as Topic; D005260:Female; D005313:Fetal Death / Q000097:blood; D005316:Fetal Distress / Q000097:blood; D005966:Glucuronidase; D006801:Humans; D010920:Placenta / Q000378:metabolism; D010926:Placental Hormones / Q000097:blood*; D011225:Pre-Eclampsia / Q000097:blood; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D011786:Quality Control; D011863:Radioimmunoassay
chemical_list: D004967:Estrogens; D004966:Estrogens, Conjugated (USP); D010926:Placental Hormones; D005966:Glucuronidase; D004964:Estriol