Laboratory Tests and Procedures
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Laboratory Tests and Procedures

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Questions and Answers

Which factor is known to increase the concentration of analytes in a specimen after food ingestion?

  • Tourniquet application
  • Diet-related changes (correct)
  • Exercise
  • Tobacco smoking
  • What is a potential effect of vigorous hand exercise, such as fist clenching, on potassium levels?

  • Decreases potassium concentration
  • Increases potassium concentration (correct)
  • Has no effect on potassium level
  • Causes potassium to fluctuate unpredictably
  • Which hormone is known to show a postprandial rise in concentration after eating?

  • Insulin (correct)
  • Cortisol
  • Testosterone
  • Thyroxine
  • What type of variations are usually transient and easily controlled in laboratory tests?

    <p>Diet-related changes</p> Signup and view all the answers

    Which accrediting agency requires laboratories to document specimen collection methods?

    <p>CAP</p> Signup and view all the answers

    What is the primary reason for applying a tourniquet before specimen collection?

    <p>To induce venous constriction</p> Signup and view all the answers

    Which of the following substances is likely to show an increase in concentration due to strenuous exercise?

    <p>Creatinine</p> Signup and view all the answers

    What effect does tobacco smoking have on laboratory test results?

    <p>Can increase levels of certain analytes</p> Signup and view all the answers

    What can cause specimen quality to be compromised due to incomplete barrier formation in gel tubes?

    <p>Insufficient centrifugation</p> Signup and view all the answers

    Which of the following is a common error in specimen collection that could lead to contamination?

    <p>Wrong patient identification</p> Signup and view all the answers

    What is the most problematic additive carry-over in specimen collection?

    <p>EDTA</p> Signup and view all the answers

    How can evaporation of specimens affect electrolytes?

    <p>It can lead to electrolyte imbalances.</p> Signup and view all the answers

    Which error is associated with prolonged tourniquet application?

    <p>Hemoconcentration</p> Signup and view all the answers

    What is the potential effect of severe hemolysis on analytes present in serum or plasma?

    <p>It causes a slight dilutional effect.</p> Signup and view all the answers

    Which analytes become clinically significant after 24 hours of unseparated serum or plasma?

    <p>Albumin and total protein</p> Signup and view all the answers

    How does bilirubin interfere with serum measurements?

    <p>It causes light scattering at relevant wavelengths.</p> Signup and view all the answers

    What is a consequence of lipemia in a serum sample?

    <p>It blocks light transmission.</p> Signup and view all the answers

    Which analytic constituent is least stable if not removed from the clot within 30 minutes?

    <p>Potassium</p> Signup and view all the answers

    What corrective measure can help prevent the shift of electrolytes leading to erroneous potassium levels?

    <p>Blanking technique</p> Signup and view all the answers

    After how many hours does serum become unstable if not separated from the clot?

    <p>6 hours</p> Signup and view all the answers

    Which of the following analytes might be significantly affected by hemoconcentration?

    <p>Albumin</p> Signup and view all the answers

    What might happen to triglycerides when serum exceeds a specific concentration?

    <p>It restricts light transmission.</p> Signup and view all the answers

    Which electrolyte is prone to false increases due to shifts from high metabolic activity of white blood cells (WBCs)?

    <p>Potassium</p> Signup and view all the answers

    What is the optimal storage temperature for serum or plasma if analysis is to be delayed for longer than 4 hours?

    <p>4-6℃</p> Signup and view all the answers

    Which of the following is a reason for specimen rejection?

    <p>Presence of hemolysis/lipemia</p> Signup and view all the answers

    Which additive is specifically used to prevent blood from clotting in vacuum tubes?

    <p>Potassium oxalate</p> Signup and view all the answers

    What can excessive centrifugation lead to in specimen handling?

    <p>Hemolysis and cell lysis</p> Signup and view all the answers

    Which analytes must be chilled during transport and storage at 4℃?

    <p>Ammonia and blood gases</p> Signup and view all the answers

    What is a common effect of hemolysis on laboratory results?

    <p>Inhibition of lipase</p> Signup and view all the answers

    Which of the following is an additive in evacuated tubes that helps in clotting?

    <p>Thrombin</p> Signup and view all the answers

    What does an antiglycolytic agent do in specimen handling?

    <p>Preserves glucose levels</p> Signup and view all the answers

    Which condition could result from the movement of water into cells during specimen collection?

    <p>Hemoconcentration</p> Signup and view all the answers

    What is the effect of low temperature storage on LDH isoenzymes?

    <p>Decreased enzymatic activity</p> Signup and view all the answers

    What is a common cause of hematoma formation during venipuncture?

    <p>Removing the needle with the tourniquet still on</p> Signup and view all the answers

    Which action can lead to a hemolyzed specimen?

    <p>Shaking the blood collection tubes vigorously</p> Signup and view all the answers

    Why is skin puncture often preferred in geriatric patients?

    <p>Skin elasticity can affect blood flow</p> Signup and view all the answers

    Which factor is NOT associated with the risk of hemolysis?

    <p>Allowing alcohol to dry at the collection site</p> Signup and view all the answers

    What is the primary indication of a hematoma?

    <p>Swelling around the venipuncture site</p> Signup and view all the answers

    Which of the following is a potential complication from inappropriate blood collection in premature infants?

    <p>Iatrogenic anemia</p> Signup and view all the answers

    How should the bevel of the needle be positioned for optimal venipuncture?

    <p>Bevel facing down</p> Signup and view all the answers

    Why is capillary blood collection preferred for infants and young children?

    <p>Venipuncture can damage veins</p> Signup and view all the answers

    What is syncope more commonly referred to as?

    <p>Fainting</p> Signup and view all the answers

    Which condition must be reserved exclusively for parenteral therapy in sick infants?

    <p>Arterialized blood collection</p> Signup and view all the answers

    Which technique can contribute to the failure of blood to enter the syringe or ETS?

    <p>Incorrect bevel position</p> Signup and view all the answers

    Which of the following is a late general complication of improper blood collection techniques?

    <p>Serum hepatitis</p> Signup and view all the answers

    What can cause excessive probing during venipuncture?

    <p>Not accessing the vein correctly</p> Signup and view all the answers

    Study Notes

    Laboratory Responsibilities

    • Laboratories must establish standard procedures for patient preparation, sample collection, transportation, and preservation to minimize errors.
    • Accreditation agencies like CAP require detailed manuals documenting specimen collection methods and error minimization.

    Pre-Collection Causes of Variation

    • Factors influencing analyte concentration include tourniquet application, exercise, and tobacco smoking.
    • Diet-related changes in lab tests often result from postprandial responses, causing transient increases in various analytes.

    Hemolysis and Hematoma Prevention

    • Hemolysis can occur from using excessively small needles, rapid plunger pulls, or vigorous mixing.
    • Hematomas may develop due to needle size mismatch, excessive probing, or improper pressure application post-venipuncture.

    Capillary Blood Collection

    • Capillary punctures are preferred for infants and young children due to smaller blood volume and risks associated with venipuncture.
    • Microcapillary blood collections are essential when venipuncture is not feasible.

    Electrolyte and Analyte Stability

    • Certain substances like potassium, phosphorus, and glucose are unstable and can significantly alter lab results if not processed quickly.
    • Blood samples must be separated from clotting agents within 30 minutes to maintain analyte stability.

    Specimen Storage and Transport

    • Serum or plasma should be stored at 4-6℃ if analysis is delayed beyond four hours to prevent degradation.
    • Specific specimens require chilling (e.g., ammonia, blood gases, lactic acid) during transport.

    Additives in Evacuated Tubes

    • Additives in evacuated tubes prevent clotting and glycolysis, ensuring the integrity of the sample.
    • Common anticoagulants include EDTA, citrate, and heparin, with each having specific functions in the collection process.

    Common Errors in Specimen Collection

    • Misidentification, mislabeling, short draws, inadequate mixing, and the use of wrong anticoagulants are frequent errors.
    • Proper order of draw is critical to avoid contamination and ensure accurate results.

    General Guidelines

    • Excessive centrifugation can cause cell lysis, elevating potassium and LDH levels.
    • Electrolyte levels can be affected by evaporation prior to testing, compromising specimen quality.
    • Clear labeling, appropriate handling, and timely delivery to the lab are essential for accurate diagnostic testing.

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    Description

    This quiz covers key concepts and procedures related to laboratory tests, particularly focusing on creatinine, serum proteins, and the impact of short-term exercise on potassium levels and muscle enzymes. Understand the importance of standardized procedures in minimizing errors during patient preparation.

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