Clinical Chemistry: Introduction and Common Analytes

Intro to Clinical Chemistry

• Clinical Chemistry is a quantitative science involved with measuring the amounts of biologically important substances in body fluids.
• Clinical Chemistry links general chemistry, organic chemistry, and biochemistry with human physiology when considered a science.
• As a service, it provides objective evidence for medical decisions.
• As an industry, clinical laboratories are businesses that follow U.S. regulations and practices.

Common Analytes in the Clinical Chemistry Lab

• Common analytes tested include ions, salts, and minerals (e.g., sodium, potassium, calcium, chloride, CO2, lead, iron).
• Small organic molecules (e.g., glucose, cholesterol, uric acid) are commonly tested.
• Therapeutic drugs (e.g., vancomycin, theophylline, digoxin) are common analytes.
• Toxicology (e.g., alcohol, salicylate, acetaminophen) are common analytes.
• Drugs of abuse (e.g., cocaine, barbiturates, acetaminophen) are common analytes.
• Large molecules include transport proteins (e.g., albumin, transferrin, haptoglobin).
• Enzymes (e.g., lipase, amylase, creatinine kinase) are large molecules.
• Specific proteins (e.g., immunoglobulins, CRP, complement) are large molecules.
• Diabetes markers (e.g., Hemoglobin A1c or HbA1c) are classified as a large molecule.

Fluids Used for Clinical Chemistry Tests

• Blood, urine, CSF, amniotic fluid, saliva, synovial fluid, pleural fluid, pericardial fluid, and peritoneal fluid are typically used for clinical chemistry tests.

Regulatory Guidelines

• Clinical Laboratory Improvement Amendments (CLIA) of 1988 sets quality standards so all results are accurate, reliable, and timely no matter where the test occurs.
• Results are considered accurate when they generate results near the true value.
• Tests are considered reliable when results can be used by doctors for diagnosis.
• There are two levels of CLIA regulations: waived tests and non-waived tests.
• Waived tests are simple laboratory exams/procedures cleared by the FDA for home use, such as glucometers, oximeters, and pregnancy tests.
• Non-waived tests are moderately to highly complex, requiring operator skill, reagent preparation, automation and results interpretation.
• Guidelines for non-waived tests cover quality standards for proficiency testing, patient test management, quality control, personnel qualifications, and quality assurance.
• Occupational Safety and Health Act (OSHA) provides guidelines for safe testing processes.
• OSHA regulations include guidelines for operating safety equipment along with identifying, handling, and storing chemical hazards.
• Wearing proper personal protective equipment (PPE) minimizes the risk of acquiring diseases.

Clinical Chemistry Lab Personnel

• Clinical chemistry lab personnel perform analytical procedures, giving accurate and precise information to aid the diagnosis and treatment of patients.
• Clinical chemistry lab personnel are proficient in the use of basic supplies/equipment and have a critical understanding of fundamental concepts relating to analytical procedure.

Scope of Practice

• Clinical laboratory scientists/medical technologists: provide reliable test results to assist with the prevention, diagnosis, prognosis, and treatment of physiological and pathological conditions
  • Producing accurate test results.
  • Correlating and interpreting test data.
  • Assessing and improving existing lab test methods.
  • Designing, evaluating, and implementing new methods.
• They also design and implement cost-effective administrative procedures including services and personnel.
• Clinical lab personnel design, implement, and evaluate processes for continued education
• A quality assurance system is developed and monitored, including quality control of services and competence assurance of personnel.
• They promote the awareness and understanding of services to health-care professionals, the public, and the consumer.

Terminology

• Proficiency testing monitors accurate outcomes by analysing test samples from an external source and comparing results to those reference laboratories, which are then scored for accuracy.
• The Internal Quality Assessment Program (IQAP) ensures that test results are reproducible and correct from one measurement to another.
• The External Quality Assessment Program (EQAP) allows a comparison of a laboratory's testing to a source outside the laboratory.

Laboratory Safety Intro

• Laboratory safety includes being aware of potential hazards and knowing how to react

Potential Hazards

• Potential laboratory hazards include electric shock, toxic vapors, compressed gasses, flammable liquids, radioactive material and corrosive substances.
• Mechanical trauma, poisons, and the inherent risks of handling biologic materials also pose as potential hazards.

Primary Causes of Accidents

• Unsafe acts and environmental conditions
• Focus on self-protection and alertness.
• Staying informed, using common sense, and listening to instructions can prevent accidents.

Psychology of Safety

• Lab safety necessitates the control of all hazards in the clinical laboratory at all times, beginning with recognition of hazards
• This can be achieved through application of common sense, a safety-focused attitude, proper personal behavior, good housekeeping, as well as continual practice of good laboratory technique
• Accidents may occur from inexperience, ignoring known risks, haste, carelessness, fatigue or mental preoccupation
• Preventive measures include annual safety reviews, safety drills, general consciousness, appropriate orientation to safety rules and a safe work environment

Safety Awareness

• The Centers for Disease Control (CDC) published Universal Precautions which states blood and body fluid precautions should be used for all patients
• Potentially infectious materials include; body fluids (semen, vaginal secretions, amniotic fluid, saliva, tears, CSF, Urine, and breast milk) and unfixed tissues, organs or blood slides
• Precautions include appropriate barriers (gloves, gowns or lab coats) and engineering controls with appropriate ventilation (BSC)
• Universal practices include wearing gloves, frequent handwashing, and wearing lab coats.
• Prohibitions include; eating, drinking, smoking, applying cosmetics, and touching contact lenses in the lab.
• Inactivation can be achieved through; heat sterilization (250C for 15 minutes), Ethylene Oxide (450–500 mg/L at 55–60C), 2% Glutaraldehyde, 10% hydrogen peroxide and 5.25 hypochlorite (bleach).
• Inactivation can also be achieved through 10% of common household bleach (v/v with tap water)
• Medical technologists, phlebotomists, and pathologists should be vaccinated against HBV.
• Always use appropriate signs to identify hazards.

Safety Equipment

• Safety equipment developed to be used in the laboratory includes safety showers, eyewash stations, fire extinguishers for the event of a fire. These should be tested and inspected every 3 months.
• Mechanical pipetting devices should be used to manipulate all liquids.

Biological Safety

• Samples may be infected with infectious organisms, such as found in blood and body fluids
• Samples should be transported, handled, and processed using strict precautions.
• If splashing is likely, gloves, gowns, and face protection should be used.
• Specimens should be "capped" during centrifugation.
• Any spill of blood, body fluid, or other potentially infectious material must be cleaned up immediately.

Cleaning Infectious Material Spills

• Appropriate protective equipment must be worn.
• Use mechanical devices to pick up broken glass or sharp objects.
• Spills should be absorbed with paper towels, gauze pads, or tissue.
• Clean the spill site using a common aqueous detergent, or approved disinfectant.
• Disinfect the spill site using approved disinfectant, or disinfectant with 10% bleach using appropriate contact time.
• Dispose of all materials in appropriate biohazard containers.

OSHA

• OSHA's Blood-Borne Pathogens standard requires a written "Exposure Control Plan".
• OSHA defines three categories of exposure:
  • Category I: Daily exposure to blood and body fluids.
  • Category II: Regular exposure to blood and body fluids.
  • Category III: No exposure to blood and body fluids.
• Employers are required to offer the HBV vaccine to all personnel assigned to Category I and II.
• Bio Safety Cabinets should be installed to assist with manipulations of infectious materials.

Chemical Safety

• Safety measures must be taken against exposure to toxic chemicals using a hazard communication standard.
• This includes a hazard communication program, a chemical hygiene plan, and an inventory of hazardous substances.
• Toxic chemical safety measures: labelling of containers, information, training, and a program of hazard communication

Material Safety Data Sheet Info

• The Material Safety Data Sheet lists product name and identification, hazardous ingredients, permissible exposure limits (PEL), physical/chemical data, and health hazard data.
• In addition, carcinogenic potential, primary routes of entry, fire/explosion hazards, reactivity data, spill and disposal procedures, PPE, handling, and emergency procedures are provided in the data sheet.
• Storage and transportation precautions, chemical manufacturer's name, address, phone, and special information are found on the data sheet.

Hazard Communication Standard

• The National Fire Protection Association (NFPA) uses a specific hazard communication standard guide to help keep workers and first responders safe.

Flammable and Combustible Chemicals

• Flammable and combustible classification is defined by their flash point, the temperature at which the vapor can form an ignitable mixture with air.
• Flammable materials have a flashpoint less than 100°F.
• Combustible materials have a flashpoint at or above 100°F

Chemicals to Avoid

• Teratogenic chemicals can cause birth defects.
• Corrosive chemicals can injure skin or eyes by contact, and respiratory/gastrointestinal tracts if inhaled/ingested.
• Reactive chemicals spontaneously explode, ignite, evolve heat, or produce flammable/explosive gases.
• Carcinogenic chemicals can cause cancer.

Electrical Safety

• Malfunctioning electrical or mechanical equipment should be locked-out or tagged until serviced.
• You must know how to help a person experiencing electric shock using a non-conductive material.

Electrical Precautionary Procedures

• Use only explosion-proof equipment in hazardous atmospheres.
• Take extra care when operating high-voltage equipment, such as during electrophoresis.
• Only use properly grounded equipment (3-prong plug), and check for electrical cords.
• Immediately report any equipment malfunctions.
• Avoid working on "live" electrical equipment.
• Equipment should never be operated with wet hands.
• Know the exact location of the electrical control panel for the electricity to your work area.
• Use only approved extension cords and avoid overloading circuits.
• Routine ground checks and periodic maintenance should be performed on all equipment.

Radiation Safety

• The radiation safety policy should include both environmental and personnel protection.
• Areas where radioactive materials are used or stored must have caution signs, and traffic limited to essential personnel only.
• Records of this must be kept for length of employment plus 30 years.
• Radiation monitoring uses a film badge or survey meter, with a maximum permissible dose of 5000 mrem/year for the whole body.
• The wipe (leak) test wipes laboratory surfaces with moistened material, then the radiation is measured.

Compressed Gases Hazards

• Compressed gasses can be; fire, explosion, asphyxiation, or mechanical injuries.

Handling Compressed Gase

• Always know gas tank contents, and store tanks vertically, secured at all times.
• You should never store flammable liquids and compressed gases in the same area.
• Ensure that the proper regulator is used for the type of has in use.
• Don't attempt to control or shut off gas flow with the pressure relief regulator.
• Keep removable protection caps in place until the cylinder is in use.
• Confirm acetylene tanks are properly piped and that the gas used is incompatible with copper tubing.
• Don't force a “frozen” or stuck cylinder valve.
• Use a hand truck to transport large tanks, and check for leaks.
• Properly label cylinders, marking empty tanks.
• The fire triangle is: heat, fuel, air, and uninhibited action.

Fire Safety

• Remember the acronym TWIST to save lives during a fire emergency.
• Twist to break the safety seal and unlock the extinguisher.
• Pull out the safety pin.
• Aim at the base of the fire; stand 6-8 feet away.
• Squeeze the lever to discharge the extinguishing agent.
• Sweep the nozzle from side to side until flames are extinguished.

Fire Classes

• Class A Fires: Involve ordinary combustibles like wood, paper, and cloth.
  • Use pressurized water or dry chemical extinguishers.
• Class B Fires: Involve flammable liquids like grease, gasoline, paints, and oils.
  • Use dry chemical or carbon dioxide extinguishers.
• Class C Fires: Involve electrical equipment like motors, switches, and computers. 
  • Use carbon dioxide, halon, or dry chemical extinguishers.
• Class D Fires: Involve flammable metals like magnesium and sodium.
  • Use a specialized agent such as Metal X, covering a burning material with an extinguishing agent using a scoop. 

Cryogenic Materials

• Liquid nitrogen is the most used cryogenic fluid.
• These fluids may cause; fire or explosion, asphyxiation, pressure buildup, embrittlement of materials, and tissue damage similar to thermal burns.

Mechanical Hazards

• Centrifuges must be balanced to distribute load equally.
• Always wait until the rotor has come to a stop before opening the lid.
• Safety locks on equipment should never be rendered inoperable.
• Glass beads help eliminate bumping/overboiling when liquids are being heated.
• Infectious sharps should always be disposed of in OSHA-approved containers.

Disposal of Hazardous Materials

• The four basic techniques include; Flushing down the drain, incineration, burial in a landfill, and Recycling.

Chemical Waste Disposal

• Flush water-soluble substances down the drain with water, but never foul-smelling chemicals.
• Neutralize strong acids and bases before disposal.
• Always collect chemical samples from approved containers, and discard them responsibly.
• Incinerators specially designed for flammable materials can be used.
• Dispose of any solid chemicals in the landfill when possible.

Radioactive Waste Disposal

• Radioactive waste disposal depends on; whether the waste soluble/insoluble, it's level of radioactivity and the toxicity, and half-life of the isotopes included.

Biohazardous Waste Disposal.

• Medical waste comes from health care facilities.
• Solid waste may contain improperly treated or handled infectious diseases, and must be treated accordingly.
• Such waste may include blood and blood products, microbiologic waste, pathologic waste, and sharps.
• Treat such waste with steam, incinerate, use thermal inactivation, burial, or chemical disinfection to encapsulate the waste.
• Autoclave at 121C, 15 psi for 15-20 minutes to sterilize.

Learn about clinical chemistry, a quantitative science measuring substances in body fluids. It links chemistry and biochemistry with human physiology, providing evidence for medical decisions. Common analytes tested include ions, organic molecules, therapeutic drugs, toxicology, and drugs of abuse.