title: First trimester serum levels of the soluble transcobalamin receptor, holo-transcobalamin, and total transcobalamin in relation to preeclampsia risk.
abstract: BACKGROUND
  Human placenta expresses CD320, a receptor that ensures the uptake of holo-transcobalamin (holoTC). Soluble CD320 (sCD320) is present in the circulation and its concentration increases during pregnancy.
  
  
  OBJECTIVE
  To investigate a possible association of sCD320, holoTC and total transcobalamin (TC) with the risk of subsequent preeclampsia using serum samples from asymptomatic first trimester pregnant women. Moreover, we aimed to establish reference intervals of the aforementioned biomarkers for first trimester pregnant women who remained healthy throughout pregnancy.
  
  
  METHODS
  This study was a retrospective case-control study that we performed on biobank serum samples. Cases (n = 50) and controls (n = 198) (matched for gestational age and date of sample collection) were asymptomatic women in early pregnancy [median (range) gestational age = 10 (8-12) weeks]. Cases developed preeclampsia while the controls remained normotensive throughout pregnancy. We measured the serum concentration of sCD320, holoTC, and total TC by using in-house ELISA methods.
  
  
  RESULTS
  First trimester median concentrations of sCD320, holoTC and total TC were not significantly different between cases and controls. The odd ratio for developing preeclampsia based on exposure to low or high levels of sCD320, holoTC or total TC at first trimester was not significant. The reference intervals (2.5-97.5% percentiles (median)) derived from the controls were 50-170 (90) pmol\L for sCD320, 20-140 (70) pmol\L for holoTC and 560-1300 (810) pmol\L for total TC.
  
  
  CONCLUSIONS
  The risk of preeclampsia is not predicted by first trimester serum concentrations of sCD320, holoTC or total TC. The first trimester reference intervals for the three parameters is reported.
authors.affiliation: a Department of Clinical Biochemistry , Aarhus University Hospital , Aarhus , Denmark.
authors.forename: Omar
authors.initials: O
authors.lastname: Abuyaman
authors.affiliation: a Department of Clinical Biochemistry , Aarhus University Hospital , Aarhus , Denmark.
authors.forename: Niels
authors.initials: N
authors.lastname: Torring
authors.affiliation: b Aarhus Institute for Advanced Studies, Aarhus University , Aarhus , Denmark.
authors.forename: Rima
authors.initials: R
authors.lastname: Obeid
authors.affiliation: a Department of Clinical Biochemistry , Aarhus University Hospital , Aarhus , Denmark.
authors.forename: Ebba
authors.initials: E
authors.lastname: Nexo
mesh_terms: D000328:Adult; D058070:Asymptomatic Diseases; D016022:Case-Control Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D015870:Gene Expression; D006801:Humans; D016017:Odds Ratio; D011225:Pre-Eclampsia / Q000097:blood* / Q000175:diagnosis / Q000503:physiopathology; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011956:Receptors, Cell Surface / Q000097:blood* / Q000235:genetics; D012016:Reference Values; D012189:Retrospective Studies; D012306:Risk; D014155:Transcobalamins / Q000235:genetics / Q000378:metabolism*
chemical_list: D011956:Receptors, Cell Surface; D014155:Transcobalamins; C028176:transcobalamin receptor
keywords: Cobalamin; Vitamin B12; preeclampsia risk; pregnancy; sCD320; transcobalamin