Clinical Chemistry and Biochemical Tests
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Questions and Answers

What is the primary purpose of biochemical tests in medicine?

  • To aid in diagnosis, prognosis, monitoring, and screening (correct)
  • To provide treatment options
  • To only monitor the effects of treatment
  • To provide a definitive diagnosis

    • What is the primary goal of screening in healthcare?

  • To detect individuals with a condition before clinical symptoms appear (correct)
  • To diagnose a disease after symptoms appear
  • To monitor the progression of a disease
  • To develop new treatments for a disease

    • What is the term used when making a correct decision between diseases presenting a similar clinical picture?

  • Differential diagnosis (correct)
  • Monitoring
  • Diagnosis
  • Prognosis

    • What is an example of a biochemical test used for screening?

    <p>Analysis of newborn blood sample for Thyroid Stimulating Hormone (TSH)</p> Signup and view all the answers

    What is the primary purpose of biochemical tests in prognosis?

    <p>To predict the chance of recovery</p> Signup and view all the answers

    What is an example of a biochemical test used for monitoring?

    <p>Glycated haemoglobin</p> Signup and view all the answers

    What type of disease is targeted by screening?

    <p>Subclinical disease</p> Signup and view all the answers

    What is the main category of clinical chemistry tests that includes tests such as Sodium, Potassium, and Chloride?

    <p>Core biochemistry</p> Signup and view all the answers

    What is the term used to describe the doctor's prediction of how a patient's disease will progress?

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

    What is the purpose of serial measurements of plasma creatinine concentration?

    <p>To indicate when dialysis may be required</p> Signup and view all the answers

    What type of tests are typically referred to larger laboratories?

    <p>Specialized tests</p> Signup and view all the answers

    What is the purpose of an urgent test in the emergency lab?

    <p>To guide immediate treatment decisions</p> Signup and view all the answers

    What is an example of a complication of treatment that biochemical tests can detect?

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

    What is necessary to monitor the course of an illness?

    <p>A suitable analyte</p> Signup and view all the answers

    What is an example of a specialized test?

    <p>DNA analysis</p> Signup and view all the answers

    What is the characteristic of subclinical diseases?

    <p>They stay below the surface of clinical detection</p> Signup and view all the answers

    What is the specimen of choice for most blood tests?

    <p>Venous blood</p> Signup and view all the answers

    Why is plasma preferred over serum in some cases?

    <p>Because plasma accelerates analysis in medical emergencies</p> Signup and view all the answers

    What is the disadvantage of using plasma?

    <p>It forms fibrin clots or fragments</p> Signup and view all the answers

    When is a skin puncture used to obtain a blood sample?

    <p>When a small volume of blood is required</p> Signup and view all the answers

    What is the difference between plasma and serum?

    <p>Plasma has anticoagulants, serum does not</p> Signup and view all the answers

    Why is serum preferred over plasma in some cases?

    <p>Because serum is the specimen of choice for many assay systems</p> Signup and view all the answers

    What is the acceptable site for skin puncture in an infant younger than 1 year?

    <p>The lateral site surface of the foot</p> Signup and view all the answers

    When is whole blood required for testing?

    <p>For blood gas, ammonia, and some trace element determinations</p> Signup and view all the answers

    What does 'accurate' mean in physical science?

    <p>Capable of providing a correct reading or measurement</p> Signup and view all the answers

    What is the main difference between accuracy and precision?

    <p>Accuracy refers to the true value, while precision refers to the repeatability</p> Signup and view all the answers

    What is the best way to express the degree of precision of a measurement?

    <p>In terms of Standard Deviation</p> Signup and view all the answers

    What is the shape of the curve obtained by plotting the values from multiple analysis of a sample?

    <p>Normal frequency curve (bell-shaped, Gaussian curve)</p> Signup and view all the answers

    What is the purpose of control specimens in laboratory testing?

    <p>To ensure the accuracy of the test results</p> Signup and view all the answers

    What is an example of a situation where a measurement is precise but not accurate?

    <p>A measurement that is far from the true value but has a low degree of variability</p> Signup and view all the answers

    What is the term used to describe the proximity of a measurement to the true value?

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

    What is the term used to describe the repeatability or reproducibility of a measurement?

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

    What is the effect of EDTA on calcium concentration in blood?

    <p>Approaches zero calcium concentration</p> Signup and view all the answers

    Why should blood samples not be taken 'downstream' from an intravenous drip?

    <p>To prevent incorrect results due to infusion of substances</p> Signup and view all the answers

    What is the effect of long-term storage of blood samples on potassium and phosphate levels?

    <p>They increase</p> Signup and view all the answers

    What is the main reason for misidentified specimen in laboratory results?

    <p>Incorrect labeling of the specimen</p> Signup and view all the answers

    How does the sex of the patient affect blood hemoglobin concentrations?

    <p>Concentrations are lower in women</p> Signup and view all the answers

    What is the effect of a vegetarian diet on lipid and phospholipid concentrations?

    <p>They decrease</p> Signup and view all the answers

    What is the effect of age on bilirubin levels in infants?

    <p>They increase and peak about the fifth to seventh day of life</p> Signup and view all the answers

    What is the effect of age on blood glucose concentration in newborns?

    <p>It is lower than in adults</p> Signup and view all the answers

    Study Notes

    Clinical Chemistry and Biochemical Tests

    • Biochemical tests are used extensively in medicine for diagnosis, prognosis, monitoring, and screening.
    • The results of biochemical tests are useful to clinicians in making a differential diagnosis, confirming or rejecting a diagnosis, and predicting the course of a disease.

    Diagnosis and Prognosis

    • Diagnosis is the art of distinguishing one disease from another based on a patient's history and examination findings.
    • Biochemical and other investigations are used to distinguish between diseases with similar clinical pictures.
    • Tests may be selected to confirm or disprove a diagnosis, and biochemical tests are important for confirming or rejecting a clinical diagnosis.
    • Prognosis is a doctor's prediction of how a patient's disease will progress, based on knowledge of the disease's course in other patients and the patient's general health, age, and sex.
    • Tests used primarily for diagnosis may also provide prognostic information, such as serial measurements of plasma creatinine concentration in progressive renal disease.

    Monitoring and Screening

    • Monitoring involves sequential recording of a patient's condition to follow the course of an illness and monitor the effects of treatment.
    • Biochemical tests may be used to detect complications of treatment, such as hypokalemia during diuretic treatment.
    • Screening involves detecting individuals affected with a condition before it becomes clinically apparent, such as mass screening of newborn babies for phenylketonuria (PKU) and congenital hypothyroidism.

    Categories of Clinical Chemistry Tests

    • Core biochemistry tests: commonly requested tests of value in many patients, carried out in every biochemistry laboratory (e.g. sodium, potassium, chloride, urea, creatinine, calcium, phosphate, etc.).
    • Specialized tests: less commonly asked tests that may be referred to larger laboratories (e.g. DNA analysis).
    • Urgent tests: tests processed rapidly in emergency laboratories, such as those needed for immediate treatment decisions.

    Specimen Collection and Identification

    • Blood may be obtained from veins, arteries, or capillaries, with venous blood being the specimen of choice.
    • Skin puncture may be used to obtain a small volume of blood for a blood test, especially in infants.
    • Whole blood, plasma, or serum can be used for testing, each requiring specific collection and preparation procedures.
    • Specimen identification is critical, with errors in labeling or identification being a common source of erroneous lab results.

    Biological Factors Affecting Test Results

    • Sex of the patient: e.g. lower blood hemoglobin concentrations in women, affecting serum bilirubin concentrations.
    • Age of the patient: e.g. bilirubin levels in infants, low blood glucose concentrations in newborns.
    • Diet: e.g. vegetarianism affecting LDL and VLDL concentrations, total lipid and phospholipid concentrations.
    • Time of sample collection: e.g. cortisol levels.
    • Posture of the patient: e.g. supine vs. sitting or standing, affecting certain test results.
    • Medical history, pregnancy, drug history, and smoking can all affect test results.

    Accuracy and Precision

    • Accuracy refers to the proximity of a measurement to the true value.
    • Precision refers to the repeatability or reproducibility of a measurement.
    • A measurement can be precise but not accurate due to bias in the test method.
    • Control specimens are used to ensure the accuracy and precision of laboratory tests.

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    Introduction to Clinical Chemistry PDF

    Description

    This quiz covers the role of biochemical tests in medicine, including diagnosis, prognosis, and monitoring. Learn how clinicians use test results to make informed decisions.

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