Clinical biochemistry (Lec 7) (Set 1)

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30 Questions

Which term is another name for Clinical Biochemistry?

Chemical Pathology

What are the main purposes of clinical biochemistry tests?

Diagnosis and disease screening

What type of specimens are commonly used for clinical biochemistry tests?

Serum and plasma

What is the purpose of a preservative in a urine specimen for biochemical analysis?

To stabilize certain metabolites

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

Provide the correct specimen and a completed form

What do clinical biochemistry tests measure?

Quantitative changes in body fluids

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

Diabetes mellitus

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

To measure cardiac biomarkers

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


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

To ensure correct sample identification

Which of the following best defines precision in analytical testing?

The reproducibility of test results

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

To monitor the performance of the assay

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


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

A result outside the reference range, but the person is healthy

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

All of the above

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

To provide rapid reassurance or further investigations

What are some potential problems with biochemical specimens?

All of the above

Which of the following is considered a core biochemical test?


What are some examples of specialized tests in laboratory analysis?

All of the above

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

To compare test results with other laboratories

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


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


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


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


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


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


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


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


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


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.


Study Notes

Clinical Biochemistry Lab

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


  • 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.

Test your knowledge of clinical biochemistry and its importance in diagnosing and monitoring diseases. Learn why doctors request specific tests based on patient symptoms, signs, and medical history.

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