cc

• Clinical Chemistry


  • Most automated area of the laboratory
  • Instruments are computerized and designed to perform single and multiple tests from small amounts of specimen
• Clinical Chemistry


  Chemical Pathology, Medical Biochemistry, Clinical Biochemistry, Pure Chemistry
• Clinical Chemistry


  A branch of Medical science that study biochemical processes associated with health and disease
• Disciplines involved in Clinical Chemistry

  • Biochemistry
  • Computers
  • Instrumentation
  • Immunology
  • Toxicology
  • Pharmacology
  • Endocrinology
  • Analytical Chemistry
• Clinical Chemistry


  A quantitative science that is concerned with measurement of amounts of biologically important substances (called analytes) in body fluids
• Common Analytes in The Clinical Chemistry Laboratory

  • Iron, Salts and Minerals
  • Small Organic Molecules
  • Metabolites
  • Therapeutic Drugs
  • Toxicology
  • Drugs of Abuse
  • Large Molecules
  • Transport proteins
  • Enzymes
  • Specific proteins Diabetes Marker
• Areas in clinical chemistry

  • General or automated chemistry
  • Electrophoresis
  • Toxicology
  • Immunochemistry
• Sample Collection and Handling

  • Tests are performed primarily on SERUM collected in gel barrier tubes, but the serum may also be collected in tubes with red, green, gray, or royal blue stoppers
  • Also performed on plasma, urine, and other body fluids
  • Serum and plasma are obtained by centrifugation, which should be performed within 1 to 2 hours of collection
  • Differences in the appearance or color of a specimen may adversely affect the test results
• Specimens of concern


  • Hemolyzed specimens
  • Icteric specimens
  • Lipemic specimens
• Fasting samples drawn from patients who have not eaten for 8 to 12 hours are preferred
• Serum separator tubes


  • Contain an inert gel that prevents contamination of the specimen by RBCs or their metabolites
  • Samples must be allowed to clot fully before centrifugation to ensure complete separation of the cells and serum
  • Many chemistry tests require special collection and handling procedures, such as chilling and protection from light
• Collection Priorities


  • Routine Samples
  • ASAP Samples
  • Stat Samples
• Routine Samples


  Tests that are ordered by the health-care provider to diagnose and monitor a patient's condition, usually collected early in the morning but can be collected throughout the day during scheduled "sweeps" (collection times) on the floors or from outpatients
• ASAP Samples


  The response time for the collection of this test sample is determined by each hospital or clinic and may vary by laboratory tests
• Stat Samples


  Highest priority, ordered from the emergency department or for a critically ill patient whose treatment will be determined by the laboratory result, must be delivered to the laboratory promptly and the laboratory personnel notified
• Fasting Samples


  • The patient must only have refrained from eating and drinking (except water) for 12 hours
  • Drinking water is encouraged to avoid dehydration in the patient, which can affect laboratory results
  • Test results most critically affected in a non-fasting patient are those for glucose, cholesterol, triglycerides, or lipid profiles
  • It is the responsibility of the phlebotomist to determine whether the patient has been fasting for the required length of time
• Timed Samples


  Requisitions are frequently received requesting that blood be drawn at a specific time, phlebotomists should arrange their schedules to be available at the specified time and should record the actual time of collection on the requisition and sample tube
• Glucose Tolerance Tests


  For the diagnosis of diabetes mellitus and gestational diabetes, includes the 2-hour postprandial (pp) glucose test and the classic glucose tolerance test (gtt)

  
• GTT Preparation


  • Before the test, patients should be instructed to eat a balanced diet that includes 150 g per day of carbohydrates for 3 days and to fast for 12 hours but not more than 16 hours
  • Certain medications can interfere with the test results

  
• 1. Hour Oral Glucose Tolerance Test


  Recommended method for the diagnosis of diabetes mellitus, requires the collection of a fasting glucose sample, having the patient drink a 75-g glucose solution within 5 minutes and return for an additional glucose test in 2 hours

  
• One-step method for Gestational Diabetes

  Utilizes the same procedure as the diagnostic OGTT used to diagnose diabetes mellitus
• Two-step method for Gestational Diabetes

  Requires the patient to receive two tests, first a 50 - g glucose challenge load is administered to the fasting patient and blood collect and tested at 1-hour postingestion, the second test is administered on a different day and consists of either a 75 - x OGTT or a 100 - g 3-hour OGTT

  
• Lactose Tolerance Test


  Evaluates a patient's ability to digest lactose, a milk sugar, the patient is asked to drink a standardized amount of lactose solution based on body weight in place of the glucose, glucose levels will raise no more than 20 mg/dl from the fasting sample result if the patient is lactose intolerant