title: The robustness of the Roche 2nd generation homogenous HDL cholesterol (PEGME) method: assessment of the effect of serum sample storage for up to 8 years at -80 degrees C.
abstract: BACKGROUND
  Low HDL-cholesterol (HDL-C) is a strong and independent cardiovascular risk factor. Clinical trials often necessitate storage of samples before assay. Results are lacking for longer-term storage with quantification of HDL-C using different methods before and after storage.
  
  
  METHODS
  Serum samples (n=2936) from the Collaborative Atorvastatin Diabetes Study in which HDL-C had been determined on 'fresh' samples using the MnCl(2)/heparin method before freezing and storage for up to 8 years at -80 degrees C were thawed and HDL-C was determined using the Roche direct method. We participated in the Riqas QC programme and results obtained for the control serum samples using a CDC-approved method were used to generate a regression equation and thus to adjust both original results, obtained after precipitation and also to align the direct HDL-C results.
  
  
  RESULTS
  CDC-aligned HDL-C results for stored samples were lower than CDC-aligned HDL-C results before storage (mean [S.E.M.]: 1.41 [0.01] vs. 1.43 [0.01] mmol/L; P<0.0001, n=2936). Although results after storage tended to be lower, there was no significant time-dependent change in the ratio of original to stored results for HDL-C.
  
  
  CONCLUSIONS
  The study establishes that the Roche 2nd generation PEGME method is robust and eminently suitable for determinations of HDL-C in stored serum samples.
authors.affiliation: Cardiovascular Research Group, Division of Cardiovascular and Endocrine Sciences, Core Technology Facility (3rd Floor), University of Manchester, Manchester, UK. valentine.menys@manchester.ac.uk
authors.forename: Valentine
authors.initials: V
authors.lastname: Charlton-Menys
authors.forename: Yifen
authors.initials: Y
authors.lastname: Liu
authors.forename: Ashley
authors.initials: A
authors.lastname: Moorhouse
authors.forename: Paul N
authors.initials: PN
authors.lastname: Durrington
mesh_terms: D008076:Cholesterol, HDL / Q000097:blood*; D005615:Freezing; D006801:Humans; D011933:Reagent Kits, Diagnostic; D015203:Reproducibility of Results; D013048:Specimen Handling; D013997:Time Factors
chemical_list: D008076:Cholesterol, HDL; D011933:Reagent Kits, Diagnostic