title: Reference change values for insulin and insulin-like growth factor binding protein-1 (IGFBP-1) in individuals with varying degrees of glucose tolerance.
abstract: BACKGROUND
  The reference change value (RCV) is an important parameter of biological variation used to assess the significance of differences between consecutive results obtained in a single individual. This study evaluated the RCV for insulin-like growth factor binding protein-1 (IGFBP-1) and fasting serum insulin (FSI) in individuals with different degrees of glucose tolerance.
  
  
  METHODS
  IGFBP-1 and FSI concentrations were measured in 33 fasting subjects who had two blood samples taken 10 days apart. Subjects were distributed in the following categories: Normal glucose tolerance (NGT), n = 15, impaired fasting glucose (IFG), n = 9 and impaired glucose tolerance (IGT), n = 9.
  
  
  RESULTS
  The RCV values for IGFBP-1 were 59.9%, 83.2% and 93.0% and for FSI were 68.5%, 79.0% and 93.4% for subjects with NGT, IFG and IGT respectively.
  
  
  CONCLUSIONS
  The RCVs for IGFBP-1 and FSI increase with deteriorating glucose tolerance. When monitoring IGFBP-1 and FSI, changes in concentrations should be interpreted using glycaemic category-specific RCV values.
authors.affiliation: a Department of Pathology , King Abdulaziz Medical City, Jeddah.|b King Abdullah International Medical Research Center , Jeddah, Saudi Arabia.
authors.forename: Anwar
authors.initials: A
authors.lastname: Borai
authors.affiliation: c Faculty of Health & Medical Sciences, University of Surrey , UK.|d Clinical Biochemistry Department, Royal Surrey County Hospital , Guildford, UK.
authors.forename: Callum
authors.initials: C
authors.lastname: Livingstone
authors.affiliation: e Division of Medical Education, Brighton and Sussex Medical School , Brighton, UK.
authors.forename: Gordon
authors.initials: G
authors.lastname: Ferns
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D005215:Fasting / Q000097:blood; D018149:Glucose Intolerance / Q000097:blood*; D006801:Humans; D007328:Insulin / Q000097:blood*; D007333:Insulin Resistance; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000097:blood*; D008875:Middle Aged; D012016:Reference Values
chemical_list: D001786:Blood Glucose; C032231:IGFBP1 protein, human; D007328:Insulin; D018970:Insulin-Like Growth Factor Binding Protein 1
keywords: CVi; IGFBP-1; RCV; insulin; intra-individual variation; reference change value