title: Second-trimester diurnal variation of maternal serum alpha-fetoprotein, human chorionic gonadotropin, and unconjugated oestriol: is it present and does it affect the prediction of a patient's risk for fetal Down syndrome?
abstract: Both a cross-sectional and a longitudinal study were performed to investigate whether or not the collection time should be taken into consideration when generating a patient's risk for fetal Down syndrome with multiple marker screening. Diurnal variations of third-trimester alpha-fetoprotein (AFP) levels and first-trimester human chorionic gonadotropin (hCG) levels have been previously reported. In addition, large episodic fluctuations of conjugated and unconjugated oestriol (uE3) as well as a diurnal variation have also been reported in the third trimester. If the levels of these analytes routinely fluctuate during the day, they could affect a patient's risk calculation for fetal Down syndrome. The longitudinal study evaluated ten non-diabetic women who underwent sequential sampling for AFP, hCG, and uE3. The cross-sectional study evaluated 1953 patients for these three markers whose time of sampling was recorded between 8.00 a.m. and 5.59 p.m. Using either study design, no significant effect was seen in the median MOM levels of the screening analytes as a function of the time of day.
authors.affiliation: Department of Obstetrics and Gynecology, University of Pennsylvania Medical Center, Philadelphia 19104.
authors.forename: N C
authors.initials: NC
authors.lastname: Rose
authors.forename: J A
authors.initials: JA
authors.lastname: Canick
authors.forename: G J
authors.initials: GJ
authors.lastname: Knight
authors.forename: A
authors.initials: A
authors.lastname: Pulkkinen
authors.forename: M B
authors.initials: MB
authors.lastname: Tumber
authors.forename: M T
authors.initials: MT
authors.lastname: Mennuti
authors.forename: G E
authors.initials: GE
authors.lastname: Palomaki
mesh_terms: D015415:Biomarkers; D001800:Blood Specimen Collection; D006063:Chorionic Gonadotropin / Q000097:blood*; D002940:Circadian Rhythm / Q000502:physiology; D003430:Cross-Sectional Studies; D004314:Down Syndrome / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology; D004964:Estriol / Q000097:blood*; D005260:Female; D005315:Fetal Diseases / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology; D006801:Humans; D008137:Longitudinal Studies; D011237:Predictive Value of Tests; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011296:Prenatal Diagnosis; D012307:Risk Factors; D013997:Time Factors; D000509:alpha-Fetoproteins / Q000032:analysis*
chemical_list: D015415:Biomarkers; D006063:Chorionic Gonadotropin; D000509:alpha-Fetoproteins; D004964:Estriol