title: Evaluation of a homogeneous assay for measuring LDL-cholesterol in hyperlipidemic serum specimens.
abstract: OBJECTIVE
  Homogeneous assay reagents for the determination of low-density lipoprotein cholesterol (LDL-C) have been available from several manufacturers. However, there has been considerable controversy due to uncertainty regarding their reactivity with intermediate-density lipoprotein (IDL), which is detected at an especially high frequency in patients with type III hyperlipemia. In this study, we examined the reactivity of a homogeneous assay, Cholestest LDL (R) (CT-LDL), with hyperlipemic sera that were classified according to the WHO system.
  
  
  METHODS
  Sera from 6 normolipidemic and 22 hyperlipidemic patients classified according to the WHO system were used for this study. All serum specimens were fractionated by the ultracentrifugation method of Hatch and Lees, and subjected to lipid and protein measurements.
  
  
  RESULTS
  The percent bias of values measured by CT-LDL relative to those determined by the ultracentrifugation method was calculated and compared to the lipid/protein ratios of each lipoprotein fraction. Consequently, the coefficient of correlation between the bias and the Triglyceride/Total cholesterol (TG/TC) ratio in the IDL fraction was 0.742. There were also correlations with the TG/TC ratio and the apo-lipoprotein B/Total Cholesterol ratio in the LDL fraction and in the LDL+IDL fraction, respectively.
  
  
  CONCLUSIONS
  Further testing will be required in order to know more about the clinical condition of hyperlipidemic patients, since CT-LDL may react differently with some beta lipoproteins having a diverse lipid/protein composition compared to those in normolipidemic specimens.
authors.affiliation: Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, Japan. shizu@imed2.osaka-u,ac,jp
authors.forename: Shizuya
authors.initials: S
authors.lastname: Yamashita
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Nakamura
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Koizumi
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Oku
authors.forename: Jose C
authors.initials: JC
authors.lastname: Sandoval
authors.forename: Kazumi
authors.initials: K
authors.lastname: Tsubakio-Yamamoto
authors.forename: Miyako
authors.initials: M
authors.lastname: Kawase
authors.forename: Daisaku
authors.initials: D
authors.lastname: Masuda
authors.forename: Masahiro
authors.initials: M
authors.lastname: Koseki
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Matsuura
authors.forename: Iichiro
authors.initials: I
authors.lastname: Shimomura
authors.forename: Makoto
authors.initials: M
authors.lastname: Nishida
authors.forename: Masato
authors.initials: M
authors.lastname: Ishigami
mesh_terms: D001681:Biological Assay / Q000592:standards*; D002784:Cholesterol / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood*; D006801:Humans; D006949:Hyperlipidemias / Q000097:blood* / Q000175:diagnosis*; D008074:Lipoproteins / Q000097:blood; D015203:Reproducibility of Results; D014280:Triglycerides / Q000097:blood; D014461:Ultracentrifugation
chemical_list: D008078:Cholesterol, LDL; D008074:Lipoproteins; D014280:Triglycerides; C030104:lipoprotein cholesterol; D002784:Cholesterol