07 Clinical Chemistry

• Clinical Chemistry is also known as:

  • chemical pathology
  • medical biochemistry
  • clinical biochemistry
• Clinical Chemistry

  The systematic study of biochemical processes associated with health & disease & the measurement of constituents in body fluids or tissues to facilitate timely, relevant, accurate and precise diagnosis of disease monitor the effect of treatment and measuring the drug levels in blood and other body fluids.
• Clinical Chemistry

  • monitor the effect of treatment and measuring the drug levels in blood and other body fluids
• Scope/Areas of Interest of Clinical Chemistry:

  • Biochemistry
  • Endocrinology
  • Immunology
  • Pharmacology
  • Toxicology
  • Computers
  • Instrumentation
  • Analytical Chemistry
• CURRENT INTERESTS:

  1. Indicators of a Healthy Lifestyle: (regular check-ups)

  • Cholesterol
  • Blood Sugar
• CURRENT INTERESTS:

  2. Predictors of a Heart Disease

  • Lipoproteins
• CURRENT INTERESTS:

  3. Markers of Mental Illness or Cancer

  • Cortisol
  • Alfa Feto Protein (AFP)
• CURRENT INTERESTS:

  4. Disease Specific Protein Markers

  • C-reactive Protein
  • Ceruloplasmin
• CURRENT INTERESTS:

  5. Nutritional Assessment

  • the healing process
  • mineral status
• CURRENT INTERESTS:

  6. Treatment Monitoring

  • LFTs in ARV Therapy
• CURRENT INTERESTS:

  7. General Maintenance of Health
• Pre-requisites of clinical chemistry Work:

  • The scientific notation of use of (systeme internationale) SI units
• Pre-requisites of clinical chemistry work"

  • Ability to make bake basic computations applicable to the clinical chemistry laboratory
• Pre-requisites of clinical chemistry work:

  • Availability and use of quality water: one that meets specific requirements
• Pre-requisites of clinical chemistry work:

  • Availability and use of quality chemicals, reagents and consumable supplies
• Pre-requisites of clinical chemistry work:

  • Adherence to collection, transport, handling and processing or testing of specimens
• Pre-requisites of clinical chemistry work:

  -Application of safety and quality assurance measure in clinical chemistry laboratory work
• Henry Bence Jones

  • looked back on experiments of Antoine-Laurent de Lavoisier in pneumatic chemistry.
• Robert James Graves (1796-1853)

  • “few and scanty, indeed, are the rays of light which chemistry has flung on the vital mysteries.
• Friedrich Wohler (1800)

  • Synthesis of urea. exploration of life phenomenon to replace the misconception that ‘life was but a series of chemical reactions’
• 1815

  • urine test for diabetes and carbohydrate metabolism investigations started
• Johann Joseph Scherer (1814-1869)

  • first used the term “ clinical chemical laboratory (klinisch chemischem Laboratorium)
• Max Josef von Pettenkofer (1818-1901)

  • complained that clinicians do not use their chemistry laboratory services except when needed for “luxurious embellishment for a clinical lecture.”
• Donald D. van Slyke (1883-1971)

  • an outstanding clinical chemist able to give an excellent interpretation of analytical results obtained from in BODY FLUIDS. Published a BOOK in 1932 along with John P. Peeters entitled Clinical Chemistry. He is also the FOUNDER of Modern Clinical Chemistry.
• 19th Century - Crude techniques but advances to understand the living material were made despite limitations.

  1. discovery of starch, fats and some blood proteins were isolated and characterised
  2. Cholesterol in gall stones
  3. Chemical composition of urine
• Further developments in the 1900s:

  • Ph meter -initially for citrus acidity testing but adapted to pH in assays
• Further developments in the 1900s:

  • Colorimeters -electronic measurement replaced visual comparison reacted tests with standard solutions i.e. objectivity replaced subjectivity
• Dr. L. Skeggs

  • discovered the Technicon Autoanalyser
• 1970

  • Radioisotopes were used in assay Scintillation counting devices
• Incorporation or linkage of computers to laboratory equipment:

  • ability for data processing
  • monitoring of data produced
  • ensured accuracy
  • correlations and relationships with previous information (Delta check)
• Clinical chemistry tests are performed primarily on serum collected in gel barrier tubes.
• Tests are also performed on:

  • plasma
  • CSF
  • Urine
  • Synovial fluid
  • Pleural Fluid
  • Pericardial Fluid
  • Peritoneal Fluid
• Serum and plasma are obtained by centrifugation (for 10 mins).
• For acquiring serum, blood samples must be allowed to clot fully (takes about 20–30 minutes) before centrifugation to ensure complete separation of the cells and serum.
• Serum or plasma should be separated from cells as soon as possible.
• Ideally, all measurements should be performed within 1 hour after collection.
• Serum or plasma must be stored at 4 ° C to 6 ° C or freeze at -20 ° C, if analysis is to delayed by more than 4 hrs.
• During storage (ambient temperature, refrigeration or freezing), the concentration of a blood constituent in the specimen may change as a result of various processes, including adsorption to glass or plastic tubes, protein denaturation, water movement into cells resulting in hemoconcentration of serum and plasma, etc.
• Interfering Conditions in the Measurement of Analytes:

  • Hemolyzed Specimen
  • Icteric Specimen
  • Lipemic Specimen
• Hemolyzed Specimen

  • Appear red because of the release of hemoglobin from RBCs
  • Severe hemolysis causes a slight dilutional effect on the analytes present in serum or plasma.