title: Should we measure serum or plasma lead concentrations?
abstract: METHODS
  Serum samples may not be appropriate to assess lead (Pb) concentrations because they may contain artificially higher Pb concentrations compared with those measured in plasma samples. Here, we compared Pb concentrations in serum versus heparin plasma separated from blood collected with or without vacuum. We have also examined the effects of sample standing time on Pb concentrations measured in serum, heparin plasma, and EDTA plasma.
  
  
  METHODS
  We studied plasma and serum samples from twelve healthy subjects. Blood samples were collected via venous drainage phlebotomy with and without vacuum into trace metal free tubes containing no anticoagulants (serum), or lithium heparin, or EDTA (to obtain plasma). Variable sample standing times (0, 5, and 30 min) prior to centrifugation were allowed. Plasma and serum Pb and iron concentrations were determined by inductively coupled plasma mass spectrometry. Plasma and serum cell-free hemoglobin concentrations were measured.
  
  
  RESULTS
  Pb concentrations in serum and in heparin plasma from blood samples collected with or without vacuum were similar and not associated with significant changes in iron or hemoglobin concentrations. The sample standing time (up to 30 min) did not affect Pb concentrations in serum or in heparin plasma, which were approximately 50% lower than those found in EDTA plasma.
  
  
  CONCLUSIONS
  Serum or heparin plasma separated from blood samples collected via venous phlebotomy with or without vacuum are appropriate medium to assess Pb concentrations, independently of the sample standing time.
authors.affiliation: Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas, Campinas, SP, Brazil.
authors.forename: Vania B
authors.initials: VB
authors.lastname: Rezende
authors.forename: Jefferson H
authors.initials: JH
authors.lastname: Amaral
authors.forename: Raquel F
authors.initials: RF
authors.lastname: Gerlach
authors.forename: Fernando
authors.initials: F
authors.lastname: Barbosa
authors.forename: Jose E
authors.initials: JE
authors.lastname: Tanus-Santos
mesh_terms: D000328:Adult; D001800:Blood Specimen Collection; D004492:Edetic Acid; D006801:Humans; D007854:Lead / Q000097:blood*; D010949:Plasma / Q000737:chemistry*; D044967:Serum / Q000737:chemistry*; D013054:Spectrophotometry, Atomic / Q000379:methods*; D013997:Time Factors; D055815:Young Adult
chemical_list: D007854:Lead; D004492:Edetic Acid