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How Reliable is Laboratory Testing?

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For many people, clinical laboratory testing is an unfamiliar side of medical care. Yet many of the decisions your an your healthcare provider make about your health status – obtaining a diagnosis, developing a course of action for treatment, or monitoring your body's response to therapy – are based on laboratory data.

Your provider trusts the results coming from the laboratory and that trust is well-placed. Clinical laboratory testing is held to very high state and federal regulatory standards.

  • All laboratory test methods must meet scientifically rigorous criteria before they can be used in clinical practice. For commercial tests in the U.S., the Food and Drug Administration (FDA) reviews the scientific evidence to ensure that:
    • the test is accurately able to detect or measure the substance it claims to detect or measure, and
    • the measurement or detection of this substance provides important information about an illness or about health status that assists in the diagnosis, treatment, or monitoring of a patient.

For more on the regulation and evaluation of test development, see the article Putting New Laboratory Tests into Practice: Regulation.

  • A laboratory must demonstrate that it is able to perform that test in a clinically acceptable way. State and federal regulatory agencies monitor the laboratory and set standards that a laboratory must meet in order to be allowed to perform the test. Some of these standards are:
    • Laboratories must perform routine quality control tests, usually every day, and in many cases, several times a day. Quality control tests usually include normal and abnormal samples to ensure that the equipment, the technologist, and the reagents used in the test are performing to established standards.
    • Laboratories must participate in proficiency testing programs in addition to quality control testing. For proficiency testing, an external agency sends "challenge" samples to be tested. The laboratory must report results back to the agency. The agency has already evaluated each of the challenge samples and knows the expected results. This evaluation also compares results to other participating laboratories, noting similarities or differences that may be attributed to the testing methodologies used. The laboratory must get the right result in order to be allowed to continue to test patient samples. If the lab repeatedly fails to get the right result, it is prohibited from continuing the performance of that test until it can demonstrate that it has corrected the problems that led to the unacceptable results.
    • Laboratories must demonstrate that they have written policies and procedures in place to specifically document how the sample is collected, transported, evaluated, and reported in an appropriate manner.

These requirements ensure that the tests performed by clinical laboratories for patient care will generate results that are reproducible and can be trusted.

For additional details on standards set for laboratories, see the article Lab Oversight: A Building Block of Trust, Regulations: The Key Players.

Some of the statistical indicators that are used to assure that both the test method and the laboratory performing the test are meeting acceptable standards are described in the next few pages, along with descriptions of other ways in which laboratories assure reliability. In addition, the following link to another article on Lab Tests Online provides additional details on specific concepts and practices that contribute to the trust placed in laboratory tests.

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