Use of total patient data for indirect estimation of reference intervals for 40 clinical chemical analytes in Turkey

Ilcol Y. O., Aslan D.

CLINICAL CHEMISTRY AND LABORATORY MEDICINE, vol.44, no.7, pp.867-876, 2006 (SCI-Expanded) identifier identifier identifier


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, g-glutamyltransferase (g-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.