Reference intervals are fundamental tools used in the clinical environment to interpret patient laboratory test results and consequently, for clinical decisions. They most commonly represent the central 95 % of laboratory test results expected in a reference population. Under optimal conditions, a laboratory should perform its own study to establish reference intervals specific for its method and local population. Despite the rapid progress of laboratory biomedicine, we do not have universally standardized reference intervals, due to differences in population and methodologies among laboratories. Differences in reference intervals between laboratories may be larger or smaller. Larger studies and a large number of suitable volunteers are needed, to establish reference intervals, so it makes sense to use them in multiple laboratories. Laboratories can receive reference intervals for tumour markers from various sources (manufacturers package inserts, multicentre studies, published national or international expert panel recommendations, guidelines, local expert groups or data mining of existing data). It is recommended that each laboratory conducts a survey of comparability of transferred reference intervals for local population and its methodology in order to maximize the quality of laboratory results. The process of transferring reference intervals from external sources, together with the assessment and validation of suitability, is called verification. The process of verifying reference intervals transferred from external sources, is a quick and efficient process, to confirm the adequacy of reference values for clinical use.
The purpose of the master's thesis was to verify the reference range for selected tumour markers (NSE, S-100, cyfra 21-1, CA 72-4, AFP, CEA, CA 125, CA 15-3 in CA 19-9). In accordance with the CLSI EP28-A3c guideline recommendations we verified transferred reference intervals using a small number of healthy reference individuals from the local population. We obtained and analysed blood samples of appropriate reference individuals and focused on control of the consistency of preanalytical and analytical factors. With verification we confirmed the quality and adequacy of the transferred reference values. On the basis of the statistical analysis of the gathered information we have successfully verified the reference ranges for selected tumour markers currently in use in Specialized Laboratory for hormones and tumour markers. With verification of transferred values, we can confirm suitability for our population. We have also proven the same for the reagent manufacturer's reference values, and our measured values are within the reference limits.
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