title: A reference interval study for common biochemical analytes in Eastern Turkey: a comparison of a reference population with laboratory data mining.
abstract: BACKGROUND
  The aim of this study was to define the reference intervals (RIs) in a Turkish population living in Northeast Turkey (Erzurum) for 34 analytes using direct and indirect methods. In the present study, the regional RIs obtained were compared with other RI studies, primarily the nationwide study performed in Turkey.
  
  
  METHODS
  For the direct method, 435 blood samples were collected from a healthy group of females (N = 218) and males (N = 217) aged between 18 and 65 years. The sera were analysed in Ataturk University hospital laboratory using Roche reagents and analysers for 34 analytes. The data from 1,366,948 records were used to calculate the indirect RIs using a modified Bhattacharya method.
  
  
  RESULTS
  Significant gender-related differences were observed for 17 analytes. There were also some apparent differences between RIs derived from indirect and direct methods particularly in some analytes (e.g. gamma-glutamyltransferase, creatine kinase, LDL-cholesterol and iron). The RIs derived with the direct method for some, but not all, of the analytes were generally comparable with the RIs reported in the nationwide study and other previous studies in Turkey.There were large differences between RIs derived by the direct method and the expected values shown in the kit insert (e.g. aspartate aminotransferase, total-cholesterol, HDL-cholesterol, and vitamin B12).
  
  
  CONCLUSIONS
  These data provide region-specific RIs for 34 analytes determined by the direct and indirect methods. The observed differences in RIs between previous studies could be related to nutritional status and environmental factors.
authors.affiliation: Department of Medical Biochemistry, Ataturk University, School of Medicine, Erzurum, Turkey.
authors.forename: Ebubekir
authors.initials: E
authors.lastname: Bakan
authors.affiliation: Department of Medical Biochemistry, Ataturk University, School of Medicine, Erzurum, Turkey.
authors.forename: Harun
authors.initials: H
authors.lastname: Polat
authors.affiliation: Department of Medical Biochemistry, Uludag University, School of Medicine, Bursa, Turkey.
authors.forename: Yesim
authors.initials: Y
authors.lastname: Ozarda
authors.affiliation: Department of Medical Biochemistry, Ataturk University, School of Medicine, Erzurum, Turkey.
authors.forename: Nurinnisa
authors.initials: N
authors.lastname: Ozturk
authors.affiliation: Department of Medical Biochemistry, Ataturk University, School of Medicine, Erzurum, Turkey.
authors.forename: Nurcan Kilic
authors.initials: NK
authors.lastname: Baygutalp
authors.affiliation: Department of Medical Biochemistry, Ataturk University, School of Medicine, Erzurum, Turkey.
authors.forename: Fatma Zuhal
authors.initials: FZ
authors.lastname: Umudum
authors.affiliation: Department of Medical Biochemistry, Ataturk University, School of Medicine, Erzurum, Turkey.
authors.forename: Nuri
authors.initials: N
authors.lastname: Bakan
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001219:Aspartate Aminotransferases / Q000097:blood; D001774:Blood Chemical Analysis / Q000379:methods / Q000592:standards*; D008076:Cholesterol, HDL / Q000097:blood; D057225:Data Mining; D005260:Female; D006801:Humans; D007755:Laboratories, Hospital; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D014421:Turkey
chemical_list: D008076:Cholesterol, HDL; D001219:Aspartate Aminotransferases
keywords: Bhattacharya method; direct method; indirect method; reference intervals; regional differences