title: Short-term estimation and application of biological variation of small dense low-density lipoproteins in healthy individuals.
abstract: BACKGROUND
  A number of methods have been developed to measure small dense low-density lipoprotein cholesterol (sd-LDL-C) to evaluate atherogenic risk in the population. However, to our knowledge there are no reports about the biologic variability of these lipoproteins. Therefore, the aim of this work was to estimate sd-LDL-C biological variability, and with this information establish quality specifications, index of individuality (II) and reference change values (RCV).
  
  
  METHODS
  To estimate within- and between-subject biological variability, sd-LDL-C in serum was measured in 24 individuals (11 female and 13 male) for 5 consecutive days and then, at 2 and 3 weeks. Quality specifications, II, and RCVs were estimated according to procedures described.
  
  
  RESULTS
  Total within- and between-subject biological variability, expressed as coefficient of variation, was 9.1% and 20%. Meanwhile, within- and between-biological variability in female and men was 10.9% and 6.7%, and 22% and 17%, respectively. Desirable quality specification to the sd-LDL-C method was 4.6% for analytical imprecision, bias 5.5% and total allowable error of 11.4%; the II was 0.46 and the RCV (calculated at 95% and 99% of significance) was 27.1% and 35.7%, for the total data.
  
  
  CONCLUSIONS
  Short-term biological variability components were determined, and then used to estimate quality specifications, II and RCV for sd-LDL-C precipitation assay. To our knowledge, this is one of the first reports about sd-LDL-C biological variability, so that this information can be used as a starting point to develop long-term studies of biological variability for sd-LDL-C.
authors.forename: Julio
authors.initials: J
authors.lastname: Lara-Riegos
authors.forename: Eduardo
authors.initials: E
authors.lastname: Brambila
authors.forename: Ana
authors.initials: A
authors.lastname: Ake-Ku
authors.forename: Vanessa
authors.initials: V
authors.lastname: Villegas-Hernández
authors.forename: Carmen
authors.initials: C
authors.lastname: Quintero-Carrilo
authors.forename: Rolffy
authors.initials: R
authors.lastname: Ortiz-Andrade
authors.forename: Rubén
authors.initials: R
authors.lastname: Yza-Villanueva
authors.forename: Julio
authors.initials: J
authors.lastname: Torres-Romero
authors.forename: Patricia
authors.initials: P
authors.lastname: Lozano-Zarain
mesh_terms: D001774:Blood Chemical Analysis / Q000592:standards*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008077:Lipoproteins, LDL / Q000097:blood*; D008297:Male; D012016:Reference Values; D013997:Time Factors
chemical_list: D008077:Lipoproteins, LDL