Impact of Errors and Variability on Clinical Laboratory Test Interpretation

Test results generated in the clinical laboratory are used to inform medical decisions on a daily basis. When used properly, laboratory testing provides critically important information that allows clinicians to screen, diagnose, and monitor patients. When performed improperly at any stage in the testing process (preanalysis, during analysis, or postanalysis), laboratory tests can produce misleading results that endanger the health and safety of the patient. Prior to ordering a laboratory test, clinicians should understand the test's capabilities and inherent limitations. Biological variation of the analyte being measured, analytic error, sensitivity, specificity, and predictive value must all be considered when interpreting a laboratory test in the proper patient context. This article describes common pitfalls encountered during the laboratory testing process and discusses established practices that help maximize the benefits of clinical laboratory test results.