title: Use of total patient data for indirect estimation of reference intervals for 40 clinical chemical analytes in Turkey.
abstract: In the present study we used patient data to calculate laboratory-specific indirect reference intervals. These values were compared with reference intervals obtained for a healthy group according to recommendations of the International Federation of Clinical Chemistry and Laboratory Medicine and manufacturer suggestions. Laboratory results (422,919 records) from all subjects of 18-45 years of age over a 1-year period were retrieved from our laboratory information system and indirect reference intervals for 40 common analytes were estimated using a modified Bhattacharya procedure. Indirect reference intervals for most of the biochemical analytes were comparable, with small differences in lower [alkaline phosphatase (ALP) (male), alanine aminotransferase (ALT), creatine kinase, iron (male), total iron-binding capacity, folic acid, calcium (female), lactate dehydrogenase (LDH), lipoprotein (a) [Lp(a)], thyroid-stimulating hormone (TSH), total triiodothyronine (T(3)), direct bilirubin, apolipoprotein A-I (apoA-I), glucose, homocysteine, total cholesterol, ferritin, total protein, ceruloplasmin, sodium, blood urea nitrogen (BUN) and uric acid (female)] and/or upper limits [albumin, ALP (male), amylase, apoA-I, creatine kinase-MB (CK-MB), total iron-binding capacity, phosphorus, glucose, total cholesterol, gamma-glutamyltransferase (gamma-GT), magnesium, total protein, high-density lipoprotein cholesterol (HDL-C), total T(3), ALP (male), ALT, aspartate aminotransferase (AST) (male), direct bilirubin (male), creatine kinase, iron, folic acid (female), Lp(a), uric acid and triglycerides], to the reference intervals determined for healthy subjects in our laboratory. The indirect reference intervals, with the exception of a few parameters (creatinine, direct total bilirubin, calcium, BUN and potassium), were not similar to the reference intervals suggested by the manufacturers. We conclude that laboratory-specific reference intervals can be determined from stored data with a relatively easy and inexpensive method. Indirect reference intervals derived from stored data may be particularly suitable for the evaluation of results for the presenting population.
authors.affiliation: Department of Biochemistry, Uludag University Medical School, Bursa, Turkey. yesim@uludag.edu.tr
authors.forename: Yesim Ozarda
authors.initials: YO
authors.lastname: Ilcol
authors.forename: Diler
authors.initials: D
authors.lastname: Aslan
mesh_terms: D000293:Adolescent; D000328:Adult; D002624:Chemistry, Clinical / Q000379:methods*; D019963:Clinical Chemistry Tests; D005260:Female; D006262:Health; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D014421:Turkey