title: Lipoprotein(a)-cholesterol: a significant component of serum cholesterol.
abstract: BACKGROUND
  Lipoprotein(a) [Lp(a)] is known to be a cholesterol-rich lipoprotein, however, the contribution of Lp(a)-cholesterol [Lp(a)-C] to the serum cholesterol and LDL-C levels has not yet been fully evaluated.
  
  
  METHODS
  We determined the serum Lp(a)-C in 55 subjects with serum Lp(a) concentrations ranging from 9 to 129 mg/dl. To measure the serum Lp(a)-C concentrations, we developed an immunoaffinity gel assay; serum was incubated with Sepharose 4B gel coupled with immunoglobulin G (IgG) prepared from a polyclonal anti-Lp(a) goat antiserum. After separating Lp(a) from other lipoproteins, we determined the serum Lp(a)-C concentrations. Validation of the assay showed satisfactory results in terms of the specificity and reproducibility.
  
  
  RESULTS
  The mean cholesterol content of Lp(a), determined as Lp(a)-C/Lp(a), was 29.5±10.4%. The serum Lp(a)-C values were found to be highly correlated with the serum Lp(a) mass (r=0.923, p<0.001). At serum Lp(a) levels of over 50mg/dl, the contribution of Lp(a)-C to the serum total cholesterol was 10.2%. Further, the Friedewald formula overestimated the serum LDL-C by 20.4%.
  
  
  CONCLUSIONS
  Lp(a) contains approximately 30% cholesterol in each molecule. In subjects with markedly elevated serum Lp(a) concentrations, the Lp(a)-C values should be taken into account when evaluating the serum LDL-C.
authors.affiliation: Department of Clinical Laboratory, Toranomon Hospital, Japan.
authors.forename: Kiyoko
authors.initials: K
authors.lastname: Kinpara
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Okada
authors.forename: Akiko
authors.initials: A
authors.lastname: Yoneyama
authors.forename: Minoru
authors.initials: M
authors.lastname: Okubo
authors.forename: Toshio
authors.initials: T
authors.lastname: Murase
mesh_terms: D000368:Aged; D002784:Cholesterol / Q000097:blood*; D002846:Chromatography, Affinity; D005260:Female; D006801:Humans; D017270:Lipoprotein(a) / Q000097:blood*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results
chemical_list: D017270:Lipoprotein(a); D002784:Cholesterol