title: Extreme concentrations of high density lipoprotein cholesterol affect the calculation of low density lipoprotein cholesterol in the Friedewald formula and other proposed formulas.
abstract: OBJECTIVE
  To investigate the effect of extreme levels of high density lipoprotein cholesterol (HDL-C) in the calculation of low density lipoprotein cholesterol (LDL-C) using Friedewald's formula (FF) and other formulas proposed recently.
  
  
  METHODS
  Lipoprotein profile was performed in 2603 samples with HDL-C ≤ 20 mg/dL and 1953 samples with HDL-C ≥ 100 mg/dL.
  
  
  RESULTS
  Wilcoxon's and Student's t-tests showed significant differences (p<0.001) between calculated LDL-C by different formulas and direct determination in the two groups of HDL-C values. Passing-Bablok regression and Bland-Altman plot showed disagreement for the four formulas studied, except for Vujovic formula in the HLD-C ≥ 100 mg/dL group.
  
  
  CONCLUSIONS
  Our results suggested that none of the formulas under analysis should be used for estimating LDL-C in samples with extreme HDL-C concentrations due to absence of statistical correlation with LDL-C direct measurement.
authors.affiliation: Laboratory of Clinical Chemistry, Virgen de la Salud Hospital, Complejo Hospitalario de Toledo, Toledo, Spain. jesust@sescam.jccm.es
authors.forename: Jesús
authors.initials: J
authors.lastname: Timón-Zapata
authors.forename: Emilio José
authors.initials: EJ
authors.lastname: Laserna-Mendieta
authors.forename: Daniel
authors.initials: D
authors.lastname: Pineda-Tenor
authors.forename: Mercedes
authors.initials: M
authors.lastname: Agudo-Macazaga
authors.forename: Carmen
authors.initials: C
authors.lastname: Narros-Cecilia
authors.forename: María Jesús
authors.initials: MJ
authors.lastname: Rocha-Bogas
authors.forename: Guadalupe
authors.initials: G
authors.lastname: Ruiz-Martín
authors.forename: Manuel
authors.initials: M
authors.lastname: Gómez-Serranillos
mesh_terms: D000465:Algorithms; D050197:Atherosclerosis / Q000097:blood / Q000175:diagnosis*; D008076:Cholesterol, HDL / Q000097:blood*; D008078:Cholesterol, LDL / Q000097:blood*; D003627:Data Interpretation, Statistical; D003951:Diagnostic Errors; D006801:Humans; D018709:Statistics, Nonparametric; D014280:Triglycerides / Q000097:blood
chemical_list: D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D014280:Triglycerides