Influence of exogenous and endogenous factors on the quality of the preanalytical stage of laboratory tests (review of literature).

A literature review in the article presents an analysis of the influence of endogenous and exogenous factors on quality of preanalytical phase of laboratory testing. The review shows significance of external and internal factors influencing blood samples at preanalytical phase of laboratory testing. Among the exogenous factors considered: phlebotomy, test tubes for samples, transportation and storage. A number of factors exist at this phase that significantly affect test results. We examined these aspects of phlebotomy process: staff training, disinfectant contamination, needle diameter, needle material contamination. The review considers possible contamination with tube components and the importance of choosing the right anticoagulants and excipients. Transportation and storage of biological samples can be a source of errors at the preanalytical phase of laboratory testing. We analyzed the problem of determining the stability of analytes during storage and aspects of transportation samples by modern means. Among the endogenous factors considered: hemolysis, lipemia, icterricity, cell metabolism.. Hemolysis is one of the most frequent consequences of errors at the preanalytical phase. We analyzed importance of choosing a method for identifying hemolized tubes and the heterogeneity of bias results on different analytical systems. The review shows contribution of various classes of lipoproteins to turbidity of sample, possible preanalytical errors and impact on analytical tests. We examined possible effects of high bilirubin concentrations on analyte measurements. In the review, we also examined metabolism of some cells and its effect on samples.