Clinical biochemistry (Lec 7) (Set 1)
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Questions and Answers

Which term is another name for Clinical Biochemistry?

  • Chemical Pathology (correct)
  • Haematology
  • Blood Sciences
  • Clinical Chemistry
  • What are the main purposes of clinical biochemistry tests?

  • Diagnosis and monitoring of treatment
  • Monitoring of treatment and prognosis
  • Disease screening and prognosis
  • Diagnosis and disease screening (correct)
  • What type of specimens are commonly used for clinical biochemistry tests?

  • Serum and plasma (correct)
  • Faeces and cerebrospinal fluid
  • Sweat and saliva
  • Urine and arterial blood
  • What is the purpose of a preservative in a urine specimen for biochemical analysis?

    <p>To stabilize certain metabolites</p> Signup and view all the answers

    What is the correct process for a clinical biochemistry test request?

    <p>Provide the correct specimen and a completed form</p> Signup and view all the answers

    What do clinical biochemistry tests measure?

    <p>Quantitative changes in body fluids</p> Signup and view all the answers

    Which disease is associated with a raised blood sugar due to lack of insulin?

    <p>Diabetes mellitus</p> Signup and view all the answers

    What is the purpose of clinical biochemistry tests in relation to heart attack?

    <p>To measure cardiac biomarkers</p> Signup and view all the answers

    Which of the following is NOT a specimen commonly used for biochemical analysis?

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

    What is the purpose of bar coding in clinical biochemistry tests?

    <p>To ensure correct sample identification</p> Signup and view all the answers

    Which of the following best defines precision in analytical testing?

    <p>The reproducibility of test results</p> Signup and view all the answers

    What is the purpose of internal quality assurance samples in a laboratory?

    <p>To monitor the performance of the assay</p> Signup and view all the answers

    What percentage of the normal population is expected to fall outside the reference range?

    <p>5%</p> Signup and view all the answers

    Which of the following is an example of a false positive result?

    <p>A result outside the reference range, but the person is healthy</p> Signup and view all the answers

    Which of the following can affect the interpretation of biochemical results?

    <p>All of the above</p> Signup and view all the answers

    What is the purpose of point-of-care testing?

    <p>To provide rapid reassurance or further investigations</p> Signup and view all the answers

    What are some potential problems with biochemical specimens?

    <p>All of the above</p> Signup and view all the answers

    Which of the following is considered a core biochemical test?

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

    What are some examples of specialized tests in laboratory analysis?

    <p>All of the above</p> Signup and view all the answers

    What is the purpose of external quality assurance samples in a laboratory?

    <p>To compare test results with other laboratories</p> Signup and view all the answers

    Clinical Biochemistry lab is also known as chemical pathology and clinical chemistry.

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

    Discretionary or selective requesting by doctors is based on patient's symptoms, signs, and previous history.

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

    Blood clot is collected into blood specimen tubes depending on the requested test.

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

    Urine specimen requires a preservative to inhibit bacterial growth or acid to stabilize certain metabolites.

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

    Clinical biochemistry tests measure changes in chemical composition of body fluids quantitatively.

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

    Precision refers to how close the measured value is to the actual value.

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

    Sensitivity is a measure of how well the assay can detect very small amounts of the analyte.

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

    Quality assurance in the lab can be ensured by comparing test results to monitor performance.

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

    The reference range chosen for a specific analyte includes 99% of the values found in healthy volunteers.

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

    False positives occur when a result falls outside the reference range, but the person is healthy and within the 5% excluded in the reference range.

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

    Study Notes

    Clinical Biochemistry Lab

    • Also known as chemical pathology and clinical chemistry, applying chemical and biochemical methods to study disease.

    Samples

    • Tests are needed for diagnosis, monitoring treatment, disease screening, and prognosis.
    • Samples are usually serum from venous blood or urine.
    • Blood is collected into blood specimen tubes depending on the requested test.
    • Serum is obtained by centrifuging blood without an anticoagulant.
    • Plasma is obtained by centrifuging blood with an anticoagulant.

    Biochemical Analyses

    • Other specimens used include urine, arterial blood, faeces, cerebrospinal fluid, sweat, and saliva.

    Processing a Request

    • Correct specimen and completed clinical biochemistry form are required.
    • Appropriate information ensures correct test and patient identification.
    • Bar coding ensures correct sample identification.
    • Automated analysis provides results with minimum delay.

    Clinical Biochemistry Process

    • The laboratory process involves receiving the specimen, analyzing the sample, and returning results to the clinician.

    Clinical Biochemistry Test Results

    • Diseases cause significant changes in body fluid chemical composition.
    • Tests measure these changes quantitatively, such as:
      • Raised blood sugar in diabetes mellitus due to lack of insulin.
      • Raised blood cardiac biomarkers due to their release from heart muscle after a heart attack.

    Precision and Accuracy

    • Precision refers to reproducibility.
    • Accuracy refers to how close the measured value is to the actual value.

    Analytical Sensitivity and Specificity

    • Sensitivity refers to the minimum amount of analyte detectable by the assay.
    • Specificity refers to the assay's ability to distinguish between the requested analyte and other substances.

    Quality Assurance

    • Internal quality assurance involves daily or every-test quality control samples.
    • External quality assurance involves distributing identical samples to several labs for comparison.

    Reference Intervals/Ranges

    • Reference ranges are chosen to include 95% of healthy volunteer values.
    • 5% of the normal population will be outside the reference range.
    • Reference ranges vary slightly according to source or lab.

    False Positives and False Negatives

    • False positive: result outside the reference range, but person is healthy.
    • False negative: patient has the disease, but gives a 'normal' result.

    Biological Factors Affecting Interpretation

    • Different reference ranges for genetically male and female individuals, depending on age, pregnancy, diet, time of day, and other factors.

    Point of Care Testing

    • Rapid reassurance or further investigations convenient and clinically meaningful.
    • Range of analytes includes glucose, protein, cholesterol, urea, and creatinine, among others.

    Problems with Biochemical Specimens

    • Difficult blood sampling, insufficient specimen, errors in timing, and incorrect specimen container or storage can affect results.

    Core Biochemical Tests

    • Us & Es (Urea and creatinine & Electrolytes): sodium, potassium, chloride, bicarbonate, calcium, and phosphate.
    • LFTs (Liver function tests): Alkaline phosphatase; alanine amino transferase; bilirubin; albumin.
    • Thyroxine and thyroid stimulating hormone, H+, pCO2, pO2 (blood gases), and glucose.

    Specialised Tests

    • Specialised techniques (not offered by every hospital) include trace elements, hormones, specific proteins (e.g., tumour markers), and DNA analysis.

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