title: Apheresis affects bone and mineral metabolism.
abstract: BACKGROUND
  Apheresis is a procedure to selectively obtain blood components. For the collection process citrate is routinely used. It inhibits coagulation by binding to ionized calcium and leads to metabolic alkalosis.
  
  
  OBJECTIVE
  Whether regular apheresis affects bone and mineral metabolism is unknown. The intention of this study was to investigate 1) the acute effects of apheresis on acid-base balance, bone and mineral metabolism and 2) to compare bone mineral density (BMD) at the lumbar spine and hip of donors to matched control subjects.
  
  
  METHODS
  In this open, observational, single-center, cross-sectional study we enrolled 102 regular plasma and thrombocyte donors to pursue objective 1) and compared those to 102 matched controls (CTR) for objective 2).
  
  
  RESULTS
  Platelet donation led to significant decreases in serum ionized calcium (-17%) and phosphate (-18%), to marked increases in base excess (57%) and PTH levels (192%) during apheresis. Baseline biochemical comparisons between donors and CTR revealed significantly lower values for donors for serum calcium, albumin, and 25-hydroxyvitamin D levels. Mean Z-score at the lumbar spine adjusted for BMI, average physical activity and daily calcium intake was lower for donors (-0.28+/-0.11) when compared to CTR subjects (0.06+/-0.11, P<0.05). Total and neck femoral BMD was also lower in the donor group, however, this difference was not significant.
  
  
  CONCLUSIONS
  Exposure to citrate during the apheresis procedure acutely affects mineral and bone metabolism. Regular donations of blood components compromised BMD at the lumbar spine. If confirmed, strategies to prevent long-term effects on bone need to be formulated.
authors.affiliation: Department of Blood Group Serology and Transfusion Medicine, Medical University of Graz, Austria. karin.amrein@klinikum-graz.at
authors.forename: Karin
authors.initials: K
authors.lastname: Amrein
authors.forename: Claudia
authors.initials: C
authors.lastname: Katschnig
authors.forename: Sabine
authors.initials: S
authors.lastname: Sipurzynski
authors.forename: Tatjana
authors.initials: T
authors.lastname: Stojakovic
authors.forename: Gerhard
authors.initials: G
authors.lastname: Lanzer
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Stach
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Pieber
authors.forename: Harald
authors.initials: H
authors.lastname: Dobnig
mesh_terms: D000136:Acid-Base Equilibrium / Q000502:physiology; D000328:Adult; D015415:Biomarkers / Q000378:metabolism; D001782:Blood Donors; D015519:Bone Density / Q000502:physiology*; D003430:Cross-Sectional Studies; D004573:Electrolytes / Q000097:blood; D005260:Female; D005272:Femur Neck / Q000378:metabolism; D006801:Humans; D008159:Lumbar Vertebrae / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010956:Plasmapheresis / Q000009:adverse effects*; D010983:Plateletpheresis / Q000009:adverse effects*
chemical_list: D015415:Biomarkers; D004573:Electrolytes