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What is the primary purpose of a clinical chemistry laboratory?
Which of the following is a unit traditionally used in clinical chemistry?
What does the Système International (SI) system primarily aim to achieve?
Which statement accurately describes the components of a meaningful quantitative laboratory result?
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What is a key requirement for electronic reporting of laboratory results?
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Which of the following is NOT a physical quantity defined by the Système International (SI)?
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How many standard prefixes does the Système International (SI) use for metric measurements?
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Which tool is essential for achieving reliable results in a clinical chemistry laboratory?
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What percentage of laboratory errors can preanalytical variables account for?
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Which of the following is NOT a preanalytical variable that can affect laboratory results?
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Why is accurate patient identification critical in the preanalytical stage?
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What is the recommended fasting period for certain chemistry tests such as glucose and cholesterol?
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What is a major implication of sub-optimal specimen quality in the preanalytical stage?
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Which step is essential to ensure proper site preparation before venipuncture?
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What can happen if alcohol is not allowed to air dry before specimen collection?
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What is the primary reason preanalytical errors remain a challenge despite technological advances in laboratories?
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What is a significant change in analyte concentration that can occur due to position changes in healthy individuals?
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Which analytes are mentioned as having variation due to position changes?
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What type of variation refers to cyclic changes in the body, such as hormonal fluctuations throughout the day?
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How do serum cholesterol levels change during a female's menstrual cycle?
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What is indicated as a non-periodic change that can alter reference values of common analytes?
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What is the term for a substance that is dissolved in a liquid?
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Which calculation involves the relationship between concentration and absorbance?
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What type of blood sample is specifically used to measure blood gases and pH?
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Which phase of the testing process includes the preparation of the patient and specimen collection?
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What is the proper term for the remaining liquid after blood has clotted?
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Which of the following is NOT a type of sample typically collected for laboratory testing?
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What type of dilution technique involves repeatedly diluting a sample in a series?
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What must laboratories clearly define to minimize errors in specimen processing?
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What analytes can become elevated due to hemolysis?
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What is the maximum recommended time a tourniquet should be applied during venipuncture?
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Which analyte is likely to increase after ingesting a high carbohydrate meal?
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How does physical exercise affect creatine kinase (CK) levels?
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What dietary factor can lead to an elevated urea concentration in the blood?
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What effect does chronic stress have on hormone levels?
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Which position of the patient during blood sampling can alter analyte concentrations?
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What is a potential consequence of prolonged tourniquet application during blood collection?
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Study Notes
Clinical Chemistry
- Clinical chemistry laboratories analyze biological samples to aid in diagnosis and treatment.
- Laboratories must adhere to strict quality control measures to ensure accurate and precise results.
Units
- Laboratory results are expressed using units such as mg/dl, g/l, mmol/L, and mEq/L.
- The International System of Units (SI) is the preferred system for reporting laboratory results.
Electronic Reporting of Results
- Laboratories leverage data management systems to ensure accurate and standardized reporting.
- Each test should have a unique code, clear identification, and include the value and units.
- Reference ranges should be included for proper interpretation of results.
Solution Properties
- Solutions consist of a solute dissolved in a solvent.
- Analytes are biological solutes analyzed in clinical chemistry.
- Concentration can be expressed in various ways, including percent solution, molarity, molality, and normality.
Laboratory Mathematics and Calculations
- Common calculations include concentration, dilution, and graphing.
- Beer-Lambert Law establishes the relationship between concentration and absorbance in photometric determinations.
Specimen Considerations
- Specimen collection, handling, and processing are crucial for accurate results.
- Laboratories should have defined procedures for specimen management and error minimization.
- Specimen types include whole blood, plasma, serum, arterial blood, urine, cerebrospinal fluid, and various body fluids.
Phases of Testing Process
- The pre-analytical phase encompasses specimen ordering, collection, preparation, transportation, storage, and dispatch.
- Quality control is primarily performed during the analytical phase, which involves processing of the sample.
- The post-analytical phase includes result calculation, recording, and reporting. The pre-analytical phase is critical for ensuring reliable test results.
Pre-Analytical Variables
- Pre-analytical variables can contribute to up to 75% of laboratory errors.
- These variables occur from test ordering to sample readiness for analysis.
Examples of Pre-Analytical Variables
- Patient preparation (e.g., fasting)
- Proper sample selection
- Collection and transportation methods
- Specimen identification and details
- Appropriate test method selection
- Sample quality and labeling
Patient Identification
- Accurate patient identification is essential to prevent mislabeling and ensure proper sample collection.
- Drawing blood from the wrong patient or mislabeling the sample can lead to errors.
Patient Preparation
- Patients may need to fast or adhere to specific dietary restrictions before specimen collection.
- Some analytes, such as glucose and cholesterol, require fasting for accurate assessment.
- Diurnal variations in analytes, like cortisol, necessitate specific timing for collection.
Site Preparation
- Venipuncture site should be cleaned with alcohol in concentric circles.
- Allow alcohol to air dry prevent specimen contamination.
- Contamination can lead to hemolysis, affecting analyte levels.
Tourniquet Application and Time
- Tourniquet should be applied for no longer than one minute.
- Prolonged tourniquet time can cause hemoconcentration, affecting analyte levels.
- Remove the tourniquet when blood flow starts in the first tube.
Factors Affecting Analyte Levels
Diet
- Nutrient intake can significantly influence certain analyte levels.
- Specific dietary restrictions may be necessary for accurate assessments.
- Examples include calcium and phosphate levels after milk ingestion, glucose levels after carbohydrate intake, and triglycerides after fatty meals.
Exercise and Stress
- Physical exercise can alter enzyme activity and cause hematuria.
- Stress can increase levels of ACTH, cortisol, and catecholamines.
Posture
- Posture during blood sampling can affect analyte levels.
- Changes are more pronounced in healthy individuals moving from horizontal to upright positions.
- Analytes affected include ALT, AST, ALP, protein, and albumin.
Circadian Variation
- Analyte levels fluctuate over time, following circadian rhythm, for example, with hormones like corticosteroids and thyroid hormones.
- Biorhythmic changes can affect analyte levels, such as those associated with the menstrual cycle.
Non-Periodic Changes
- Pregnancy can alter reference value for certain analytes such as transaminases, lipids, and hormones.
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Description
This quiz covers the fundamentals of clinical chemistry, including laboratory analysis of biological samples and the importance of quality control. It also explores units of measurement, electronic reporting standards, and solution properties relevant to laboratory results.
