title: Marked effects of extreme levels of lipoprotein(a) on estimation of low-density lipoprotein cholesterol.
abstract: BACKGROUND
  Low-density lipoprotein cholesterol (LDL-C) is usually calculated using the Friedewald equation. However, this calculation method does not account for the cholesterol associated with lipoprotein(a) [Lp(a)]. Using the Dahlen equation, Li et al. have shown a strong positive correlation between serum Lp(a) levels and overestimation of LDL-C levels.
  
  
  OBJECTIVE
  To determine how the extreme levels of Lp(a) influence the LDL-C calculation.
  
  
  METHODS
  We performed a retrospective chart review of the lipid profile and Lp(a) of 223 patients (men and women). LDL-C was calculated using the Friedewald equation. Lp(a) concentrations were measured by an ELISA. Other serum lipids were measured enzymatically by standard methodology. Corrected LDL-C was calculated using the Dahlen equation.
  
  
  RESULTS
  We found that this overestimation is very significant in individuals with extreme levels of Lp(a) (mean overestimation of 40% at Lp(a) >1200mg/L).
  
  
  CONCLUSIONS
  Calculated LDL-C is markedly overestimated in patients with extreme levels of Lp(a).
authors.affiliation: Department of Pathology & Laboratory Medicine, University of British Columbia, Vancouver, Canada. Electronic address: rsaeedi@providencehealth.bc.ca.
authors.forename: Ramesh
authors.initials: R
authors.lastname: Saeedi
authors.affiliation: Department of Pathology & Laboratory Medicine, University of British Columbia, Vancouver, Canada. Electronic address: minli@hotmail.com.
authors.forename: Min
authors.initials: M
authors.lastname: Li
authors.affiliation: Department of Pathology & Laboratory Medicine, University of British Columbia, Vancouver, Canada. Electronic address: matt.allard@hli.ubc.ca.
authors.forename: Matt
authors.initials: M
authors.lastname: Allard
authors.affiliation: Department of Pathology & Laboratory Medicine, University of British Columbia, Vancouver, Canada. Electronic address: jifr@mail.ubc.ca.
authors.forename: Jiri
authors.initials: J
authors.lastname: Frohlich
mesh_terms: D002784:Cholesterol / Q000097:blood*; D005260:Female; D006801:Humans; D017270:Lipoprotein(a) / Q000097:blood*; D008297:Male; D012189:Retrospective Studies
chemical_list: D017270:Lipoprotein(a); D002784:Cholesterol
keywords: Dahlen equation; Friedewald equation; LDL-C; Lipoprotein(a)