title: The use of fasting vs. non-fasting triglyceride concentration for estimating the prevalence of high LDL-cholesterol and metabolic syndrome in population surveys.
abstract: BACKGROUND
  For practical reasons it is not easy to obtain fasting samples in large population health surveys. Non-fasting triglyceride (Tg) values are difficult to interpret. The authors compared the accuracy of statistically corrected non-fasting Tg values with true fasting values and estimated the misclassification of subjects with high low-density lipoprotein cholesterol (LDL-C) and the metabolic syndrome.
  
  
  METHODS
  Non-fasting blood was obtained from a population-based sample of 4282 individuals aged 24-75 years in the National FINRISK 2007 Study. Fasting blood samples were drawn from the same persons 3 months later. Non-fasting serum Tg values were converted into fasting values using previously published formula. LDL-C was calculated and classification of the metabolic syndrome was carried out according to three different latest guidelines.
  
  
  RESULTS
  The median (25th, 75th percentile) non-fasting serum Tg concentration was 1.18 (0.87, 1.72) mmol/L and after postprandial correction 1.06 (0.78, 1.52) mmol/L. The true-fasting serum Tg concentration was 1.00 (0.75, 1.38) mmol/L (P < 0.001) vs. non-fasting and corrected value. Bias of the corrected value was +5.9% compared with the true-fasting Tg. Of the true fasting subjects, 56.4% had LDL-C ≥ 3.00 mmol/L. When calculated using non-fasting serum Tg, the prevalence of high LDL-C was 51.3% and using statistically corrected Tg it was 54.8%. The prevalence of metabolic syndrome was 35.5% among fully fasted persons and among non-fasting subjects 39.7%, which after statistical correction of Tg decreased to 37.6% (P < 0.001 for all comparisons).
  
  
  CONCLUSIONS
  Correction of non-fasting serum Tg to fasting values plays a minor role in population studies but nevertheless reduces misclassification of calculated high LDL-C from 5.1 to 1.6% and the metabolic syndrome from 4.2 to 2.1%.
authors.affiliation: National Institute for Health and Welfare, Department of Chronic Disease Prevention, Helsinki, Finland. jouko.sundvall@thl.fi
authors.forename: Jouko
authors.initials: J
authors.lastname: Sundvall
authors.forename: Jaana
authors.initials: J
authors.lastname: Leiviskä
authors.forename: Tiina
authors.initials: T
authors.lastname: Laatikainen
authors.forename: Markku
authors.initials: M
authors.lastname: Peltonen
authors.forename: Veikko
authors.initials: V
authors.lastname: Salomaa
authors.forename: Mauno
authors.initials: M
authors.lastname: Vanhala
authors.forename: Eeva
authors.initials: E
authors.lastname: Korpi-Hyövälti
authors.forename: Jukka
authors.initials: J
authors.lastname: Lauronen
authors.forename: Georg
authors.initials: G
authors.lastname: Alfthan
mesh_terms: D015415:Biomarkers; D001786:Blood Glucose; D015992:Body Mass Index; D002784:Cholesterol / Q000097:blood; D003430:Cross-Sectional Studies; D003625:Data Collection; D005215:Fasting / Q000097:blood*; D005260:Female; D006801:Humans; D006937:Hypercholesterolemia / Q000097:blood / Q000453:epidemiology*; D008077:Lipoproteins, LDL / Q000097:blood*; D008297:Male; D024821:Metabolic Syndrome / Q000097:blood / Q000453:epidemiology*; D009765:Obesity / Q000097:blood; D015995:Prevalence; D014280:Triglycerides / Q000097:blood*
chemical_list: D015415:Biomarkers; D001786:Blood Glucose; D008077:Lipoproteins, LDL; D014280:Triglycerides; C032607:low density lipoprotein triglyceride; D002784:Cholesterol