title: Differential reactivities of four homogeneous assays for LDL-cholesterol in serum to intermediate-density lipoproteins and small dense LDL: comparisons with the Friedewald equation.
abstract: BACKGROUND
  In routine clinical laboratory testing and numerous epidemiological studies, LDL-cholesterol (LDL-C) has been estimated commonly using the Friedewald equation. We investigated the relationship between the Friedewald equation and 4 homogeneous assays for LDL-C.
  
  
  METHODS
  LDL-C was determined by 4 homogeneous assays [liquid selective detergent method: LDL-C (L), selective solubilization method: LDL-C (S), elimination method: LDL-C (E), and enzyme selective protecting method: LDL-C (P)]. Samples with discrepancies between the Friedewald equation and the 4 homogeneous assays for LDL-C were subjected to polyacrylamide gel electrophoresis and the beta-quantification method.
  
  
  RESULTS
  The correlations between the Friedewald equation and the 4 homogeneous LDL-C assays were as follows: LDL-C (L) (r=0.962), LDL-C (S) (r=0.986), LDL-C (E) (r=0.946) and LDL-C (P) (r=0.963). Discrepancies were observed in sera from type III hyperlipoproteinemia patients and in sera containing large amounts of midband and small dense LDL on polyacrylamide gel electrophoresis. LDL-C (S) was most strongly correlated with the beta-quantification method even in sera from patients with type III hyperlipoproteinemia.
  
  
  CONCLUSIONS
  Of the 4 homogeneous assays for LDL-C, LDL-C (S) exhibited the closest correlation with the Friedewald equation and the beta-quantification method, thus reflecting the current clinical databases for coronary heart disease.
authors.affiliation: Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan. shizu@imed2.med.osaka-u.ac.jp
authors.forename: Shizuya
authors.initials: S
authors.lastname: Yamashita
authors.forename: Ryota
authors.initials: R
authors.lastname: Kawase
authors.forename: Hajime
authors.initials: H
authors.lastname: Nakaoka
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Nakatani
authors.forename: Miwako
authors.initials: M
authors.lastname: Inagaki
authors.forename: Miyako
authors.initials: M
authors.lastname: Yuasa-Kawase
authors.forename: Kazumi
authors.initials: K
authors.lastname: Tsubakio-Yamamoto
authors.forename: Jose C
authors.initials: JC
authors.lastname: Sandoval
authors.forename: Daisaku
authors.initials: D
authors.lastname: Masuda
authors.forename: Tohru
authors.initials: T
authors.lastname: Ohama
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Nakagawa-Toyama
authors.forename: Akifumi
authors.initials: A
authors.lastname: Matsuyama
authors.forename: Makoto
authors.initials: M
authors.lastname: Nishida
authors.forename: Masato
authors.initials: M
authors.lastname: Ishigami
mesh_terms: D000328:Adult; D000368:Aged; D008078:Cholesterol, LDL / Q000097:blood; D019411:Clinical Laboratory Techniques / Q000592:standards*; D003327:Coronary Disease / Q000097:blood; D003924:Diabetes Mellitus, Type 2 / Q000097:blood; D006801:Humans; D006952:Hyperlipoproteinemia Type III / Q000097:blood; D008074:Lipoproteins / Q000097:blood*; D053419:Lipoproteins, IDL / Q000097:blood; D008077:Lipoproteins, LDL / Q000097:blood; D008875:Middle Aged; D008962:Models, Theoretical
chemical_list: D008078:Cholesterol, LDL; D008074:Lipoproteins; D053419:Lipoproteins, IDL; D008077:Lipoproteins, LDL