Study 4 Specimen Storage and Stability with 12 free online flashcards. Review key terms, definitions, and concepts with this interactive flashcard deck.
Why can a specimen become unsuitable after collection?
Cells may consume or release substances, proteins and nucleic acids may degrade, and microbes may multiply or die. Light, temperature, time, and evaporation can also alter measurements.
What is the goal of specimen storage and handling?
Preserve suitability for the specific test requested. A specimen unsuitable for one test may still be acceptable for another.
How should storage requirements be determined?
There is no universal storage rule. Follow the current test directory, collection-device instructions, and receiving laboratory’s requirements for specimen type, container, temperature, holding time, and preservative.
Why should specimens not be refrigerated automatically?
Refrigeration often slows cellular activity and degradation when specified, but it can affect some analytes or cause precipitation. Do not refrigerate a specimen automatically.
What handling precaution applies to frozen specimens?
Use the required temperature and container when freezing is specified. Avoid repeated freeze–thaw cycles because they can damage some analytes.
How should a light-sensitive specimen be protected?
Wrap the specimen or use an appropriate light-protective container when required, because some analytes are light-sensitive.
Why must the correct preservative and container be used?
Use only the specified preservative and container. A preservative may stabilize a specimen or support a test, but it can interfere with other tests.
What does specimen stability mean?
Stability is the period during which a specimen remains suitable for a test under specified conditions. It depends on the analyte, specimen type, container or preservative, temperature, and processing.
Can cooling restore a specimen past its stability limit?
No. Cooling or freezing does not restore a specimen after its stability limit has been exceeded.
What should be done after a delay or temperature excursion?
Document the delay or excursion and check the test-specific acceptance criteria. Assess suitability rather than assuming the specimen remains acceptable.
What determines centrifugation conditions for blood?
Follow the instructions for the specific tube, specimen, and procedure; required force and duration are not interchangeable between procedures.
Why may serum or plasma need separation from cells?
Separate serum or plasma from cells when the test instructions require it. Continued cell contact can change some measurements; avoid disturbing the cell layer or transferring cells into an aliquot.