title: Modified Levey-Jennings charts for calculated laboratory tests.
abstract: BACKGROUND
  In clinical laboratories, many test results such as low-density lipoproteins can be calculated using the results of specifically measured tests. However, quality control programs deal with only measured tests and there is no quality control procedure for calculated tests. I aimed to modify the Levey-Jennings chart for calculated tests as part of a total quality system.
  
  
  METHODS
  I developed a method using a Taylor series expansion and alternative equations to obtain the standard deviation of calculated tests and then prepared Levey-Jennings charts for these tests.
  
  
  RESULTS
  Preparation of Levey-Jennings charts for low-density lipoproteins (and other calculated tests) was simple, and using this chart increased the reliability of calculated test results.
  
  
  CONCLUSIONS
  Checking only measured tests by quality control procedures before reporting patient results may be inadequate. Preparation of Levey-Jennings charts for calculated tests as part of total quality management will increase the reliability of test results.
authors.affiliation: Abant Izzet Baysal University, Duzce School of Medicine, Department of Clinical Biochemistry, Duzce, Turkey. coskun_a2002@yahoo.com
authors.forename: Abdurrahman
authors.initials: A
authors.lastname: Coskun
mesh_terms: D002784:Cholesterol / Q000032:analysis / Q000592:standards; D008078:Cholesterol, LDL; D019411:Clinical Laboratory Techniques / Q000706:statistics & numerical data*; D006801:Humans; D015233:Models, Statistical; D011786:Quality Control
chemical_list: D008078:Cholesterol, LDL; D002784:Cholesterol