title: Increased levels of HIV RNA detected in samples with viral loads close to the detection limit collected in Plasma Preparation Tubes (PPT).
abstract: BACKGROUND
  The accurate and reliable quantification of HIV RNA is an essential part of the management of HIV infected individuals, and elucidation of factors that may affect HIV RNA measurements, such as the use of Vacutainer Plasma Preparation Tubes (PPT), is crucial.
  
  
  OBJECTIVE
  The objective of this study was to determine if plasma samples with viral loads close to the lower limit of the dynamic range of the assay collected in PPT tubes had increased levels of HIV RNA as compared to samples collected in standard EDTA tubes.
  
  
  METHODS
  HIV RNA levels were compared in 112 paired plasma samples collected in PPT and standard EDTA tubes. All samples had been frozen prior to testing.
  
  
  RESULTS
  Discrepancies between PPT and EDTA tubes did not occur for samples with high viral loads. However, in samples with viral loads close to the lower limit of the dynamic range, levels of HIV RNA detected were higher in a large proportion of PPT as compared to the corresponding EDTA plasma samples. Forty percent of plasma pairs had no detectable HIV RNA in the EDTA aliquot, but had low levels of HIV RNA in the corresponding PPT aliquot.
  
  
  CONCLUSIONS
  This prospective study underlines the need for cautious interpretation of small transient viral load changes in samples with values close to the detection limit.
authors.affiliation: VA CT Virology Reference Laboratory, VA Connecticut Healthcare System, West Haven, CT 06516, USA. brigitte.griffith@yale.edu
authors.forename: Brigitte P
authors.initials: BP
authors.lastname: Griffith
authors.forename: Donald R
authors.initials: DR
authors.lastname: Mayo
mesh_terms: D000163:Acquired Immunodeficiency Syndrome / Q000097:blood*; D006678:HIV / Q000302:isolation & purification / Q000502:physiology*; D015658:HIV Infections / Q000821:virology; D006801:Humans; D010949:Plasma; D011446:Prospective Studies; D012367:RNA, Viral / Q000097:blood*; D013048:Specimen Handling; D019562:Viral Load
chemical_list: D012367:RNA, Viral