Preanalytical Variables and Their Influence on the Quality of Laboratory Results.

While analytical standards have been developed by established quality control criteria, there has been a paucity in the development of standards for the preanalytical phase. Only recently recommendations have been published regarding the quality of samples including the definition of the optimal sample size, the use of anticoagulants and stabilizers, stability criteria regarding transport and storage and handling of hemolytic, lipemic and icteric samples. Technical recommendations regarding sampling, transport and identification have been developed by national and international consensus organizations. The development of a preanalytical quality manual takes on an urgency in the goal towards achieving total quality control. Every day the laboratory is confronted with data arising out of preanalytical errors. Ability to recognize such data is critical to maintaining total laboratory quality and will be illustrated with case studies.