title: Plasma exchange induces vitamin D deficiency.
abstract: BACKGROUND
  Plasma exchange is used in the treatment of diseases mediated by pathogenic circulating proteins, or for transplant desensitization. Its non-targeted nature results in the depletion of physiologically important molecules, and it is often complicated by hypocalcaemia.
  
  
  OBJECTIVE
  To determine the effects of plasma exchange on vitamin D binding protein (DBP) and associated vitamin D metabolites.
  
  
  METHODS
  Single-centre prospective cohort study of 11 patients.
  
  
  METHODS
  DBP and vitamin D metabolites were measured before and immediately after five plasma exchanges, and 7 and 28 days after discontinuation of plasma exchange.
  
  
  RESULTS
  Plasma exchange reduced plasma DBP concentration from 196.9 ± 53.2 to 98.5 ± 34 μg/ml (P = 0.0001), 1,25-dihydroxyvitamin D from 103 ± 52 to 42 ± 4 pmol/l (P = 0.003) and 25-hydroxyvitamin D from 49.7 ± 29 to 22 ± 9.4 nmol/l (P = 0.0017), through their removal in effluent. After 7 days, DBP and 1,25-dihydroxyvitamin D were not significantly different from baseline, but 25-hydroxyvitamin D remained significantly lower after 7 days (26.4 ± 9.8 nmol/l, P = 0.02) and 28 days (30.8 ± 15.5 nmol/l, P = 0.048). Corrected calcium decreased from 2.23 ± 0.11 to 1.98 ± 0.08 mmol/l (P = 0.0007) immediately after five treatments. Plasma calcium was significantly associated with 1,25-dihydroxyvitamin D (r(2) = 0.79, P < 0.0001).
  
  
  CONCLUSIONS
  Plasma exchange induced an acute reversible decrease in plasma 1,25-dihydroxyvitamin D, DBP, calcium and a sustained decrease in plasma 25-hydroxyvitamin D.
authors.affiliation: Divisions of Nephrology and Clinical Pharmacology, Department of Medicine, University of Cambridge, Box 118, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK. tfh24@cam.ac.uk.
authors.forename: T F
authors.initials: TF
authors.lastname: Hiemstra
authors.forename: A
authors.initials: A
authors.lastname: Casian
authors.forename: P
authors.initials: P
authors.lastname: Boraks
authors.forename: D R
authors.initials: DR
authors.lastname: Jayne
authors.forename: I
authors.initials: I
authors.lastname: Schoenmakers
mesh_terms: D000328:Adult; D000368:Aged; D002118:Calcium / Q000097:blood; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010951:Plasma Exchange / Q000009:adverse effects*; D011446:Prospective Studies; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000209:etiology*; D014809:Vitamin D-Binding Protein / Q000097:blood
chemical_list: D014809:Vitamin D-Binding Protein; D014807:Vitamin D; C097949:1,25-dihydroxyvitamin D; C104450:25-hydroxyvitamin D; D002118:Calcium