title: Estriol in pregnancy. IV. Normal concentrations, diurnal and/or episodic variations, and day-to-day changes of unconjugated and total estriol in late pregnancy plasma.
abstract: Normal values of unconjugated, total, and immunoreactive (measured without extraction) plasma estriol (E3) have been determined from radioimmunoassay data obtained in 217 uncomplicated third-trimester pregnancies. Small but significant diurnal variations in unconjugated and total plasma E3 have been observed in a study comprising 12 women who were hospitalized during late pregnancy for diabetes, toxemia, or placenta previa. The late morning decreases in unconjugated and the afternoon/evening decreases in total plasma E3 concentrations, averaging some 10 to 15 per cent, were overshadowed by considerable episodic fluctuations and may thus be clinically irrelevant. Day-to day changes of unconjugated and total plasma E3 concentrations in late pregnancy were similar and smaller than changes in urinary E3 measurements. The urinary E3/creatinine ratio, however, reducing inadequacies of 24 hour urine collections, varied less than unconjugated or total plasma E3. The data suggest that a decrease in unconjugated or total plasma E3 must exceed 40 to 45 per cent of the mean of the three preceeding determinations if it is to be considered a signal of fetal distress.
mesh_terms: D000204:Activity Cycles; D001724:Birth Weight; D002940:Circadian Rhythm; D003404:Creatinine / Q000652:urine; D004964:Estriol / Q000097:blood* / Q000502:physiology / Q000652:urine; D005260:Female; D006801:Humans; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D011863:Radioimmunoassay; D013997:Time Factors
chemical_list: D003404:Creatinine; D004964:Estriol