title: A longitudinal study of serum cobalamins and its binding proteins in lactating women.
abstract: OBJECTIVE
  To examine longitudinal changes in serum cobalamins, transcobalamin (TC) and haptocorrin (HC) during lactation and to investigate the influence of vitamin B12 supplementation on these parameters.
  
  
  METHODS
  A 9-month follow-up study.
  
  
  METHODS
  Lactating mothers (N=89) including 23 supplemented with vitamin B12 (1-18 microg/daily), 41 partly supplemented and 25 not supplemented. Blood samples collected 3 weeks (baseline) and 4 and 9 months post-partum were analysed for cobalamins, TC and HC. Both the total concentration and the cobalamin-saturated form (holo) of TC and HC were analysed.
  
  
  RESULTS
  No significant differences were observed in serum cobalamins or its binding proteins related to supplementation with vitamin B12 or the duration of lactation. Serum cobalamins remained unchanged from 3 weeks to 9 months post-partum. Total TC (holoTC) (median+/-s.e. pmol/l) decreased between 3 weeks (710+/-23 (85+/-12)) and 9 months (602+/-21 (76+/-11)) (P<0.0001 (P=0.0002)), whereas total HC (holoHC) increased from (422+/-11 (300+/-9)) at 4 months to (455+/-13 (317+/-10)) to 9 months post-partum (P<0.0001 (P<0.0001)).
  
  
  CONCLUSIONS
  We report a decrease in TC and an increase in HC during a 9-month period post-partum. No differences were observed between the vitamin B12-supplemented and the unsupplemented groups. Thus, supplementation with vitamin B12 has no impact on the circulating level of serum cobalamins or its binding proteins in a Danish population of lactating mothers.
authors.affiliation: Department of Clinical Biochemistry, Aarhus University Hospital, Aarhus Sygehus, Aarhus, Denmark. almor@as.aaa.dk
authors.forename: A L
authors.initials: AL
authors.lastname: Mørkbak
authors.forename: C H
authors.initials: CH
authors.lastname: Ramlau-Hansen
authors.forename: U K
authors.initials: UK
authors.lastname: Møller
authors.forename: T B
authors.initials: TB
authors.lastname: Henriksen
authors.forename: J
authors.initials: J
authors.lastname: Møller
authors.forename: E
authors.initials: E
authors.lastname: Nexø
mesh_terms: D000328:Adult; D004305:Dose-Response Relationship, Drug; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007774:Lactation / Q000097:blood*; D008137:Longitudinal Studies; D011485:Protein Binding; D014155:Transcobalamins / Q000378:metabolism*; D014805:Vitamin B 12 / Q000008:administration & dosage* / Q000031:analogs & derivatives / Q000097:blood*; D014803:Vitamin B Complex / Q000008:administration & dosage / Q000097:blood*
chemical_list: D014155:Transcobalamins; D014803:Vitamin B Complex; D014805:Vitamin B 12