Araştirma Makalesi (Research Article)

There are some recommendations for determination of reference intervals necessary for medical decision. We can calculate reference intervals from the data of selected healthy reference individuals by using of nonparametric and parametric methods recommended by NCCLS (National Committee for Clinical Laboratory Standards, USA) and IFCC (International Federation of Clinical Chemistry and Laboratory Medicine), respectively. Also, it can be determined from the laboratory test results of people submitted to laboratory. In this study, healthy reference individuals selected (131 male, 128 female; ages:18-40) by questionary which was prepared according to the NCCLS recommendations. For these people, the reference intervals of the selected analytes (general control panel: alkaline phosphatase, glucose, BUN, creatinine, uric acid; lipid panel: total cholesterol, HDL cholesterol, LDL cholesterol, triglycerides; thyroid panel: TSH, total T3, total T4, free T3, free T4) were estimated by using nonparametric and parametric methods. Reference intervals of these 14 analytes also were determined from the results of people (total n=4110, ages:18-40; the general control panel, n=2968; the lipid panel, n=1256; the thyroid panel, n=1113) who were submitted to our laboratory in the same period (May –August 2000). Results were compared with each other. We found that the NCCLS and IFCC recommendations which are depended on the selection of reference individuals are more useful and nonparametric method is more appropriate estimation method. We have found that some differences between the reference intervals, especially for medical decision limits, calculated from the values of reference individuals and the patients results. The method which is proposed by us for the determination of reference intervals from the data of people who were admitted to laboratory, also useful for the evaluation of clinical laboratory performance. We also believe that the national reference interval determination policy should be established for the standardization of the laboratory tests.