Personnel in the Clinical Laboratory

The medical assistant is trained to perform certain testing procedures, as well as in methods of collecting specimens that are sent to outside reference laboratories for testing. Laboratory tests are an essential part of a medical diagnosis, and they help the physician determine the most appropriate treatment. In addition, they may be performed to help the physician decide which medication to prescribe and to monitor the effects of medications. Only healthcare practitioners may request laboratory testing for a patient. The medical assistant may be responsible for a number of these testing procedures. To assume this responsibility, the medical assistant must know proper patient preparation, the procedures for each test, and the normal range of results for the test. The medical assistant must carefully follow all laboratory instructions in obtaining and labeling specimens and sending them to the laboratory. Good communication among the patient, the office staff, and laboratory personnel is important. The medical assistant should make the patient feel at ease with these procedures and thus gain the patient’s cooperation.

Clinical Laboratory Testing

Clinical laboratory testing is used in conjunction with a thorough health history and physical examination to obtain essential data for the diagnosis and management of a patient’s condition. The body is considered to be healthy when a state of equilibrium exists in the internal environment. In this state, called homeostasis, the physical and chemical characteristics of body substances (e.g., fluids, secretions, excretions) are within a certain acceptable range, known as the normal or reference range. A change in homeostasis results in abnormal test values (i.e., outside the reference range). Abnormal values for a particular test may be seen with more than one pathologic condition. For example, a decrease in hemoglobin levels in red blood cells (RBCs) is seen in iron-deficiency anemia, but also in hyperthyroidism and cirrhosis of the liver. Therefore, physicians cannot rely solely on laboratory tests to make a diagnosis; they must use a combination of data obtained from the health history and physical examination, and a number of diagnostic and laboratory results.

Tests performed in a clinical laboratory range from simple screening tests to complex profile testing. A screening test examines a particular specimen for the presence of a substance that may indicate a disease state. These types of tests are not diagnostic for any particular disease, but rather indicate that the disease state may exist. Screening tests are done routinely on patients on the basis of their age, history, or gender. They often are qualitative in that a numeric value is not attached to the result; results may simply be reported as positive or negative. The fecal occult blood test for hidden or microscopic blood in the stool is an example of a screening test. Blood is not normally found in the stool, and its presence may indicate a cancerous lesion in the colon. A positive test result indicates that blood is present, but additional testing is required to determine the source of the blood. For example, further testing or examination may reveal that the patient had her menstrual period at the time of collection of the specimen, or that she had bleeding hemorrhoids.

In a quantitative test, units of measure are attached to numeric values. These values often are represented as the amount of analyte per given volume of specimen, and it is essential that the results be reported with the units of measure. For example, in a complete blood cell count for a healthy adult, the RBCs number 5 million per cubic millimeter (5 × 10⁶/mm³), the hemoglobin value is 15 grams per deciliter (15 g/dL), and the hematocrit is 45%. Generally the units are printed on the laboratory report, but the medical assistant must always make sure that the values are consistent with the test performed.

Clinical Laboratory Improvement Amendments

In 1988 Congress passed the Clinical Laboratory Improvement Amendments (CLIA), establishing quality standards for all laboratory testing to ensure the accuracy, reliability, and timeliness of patient test results regardless of where the test is performed. A laboratory is defined as any facility that performs laboratory testing on specimens derived from humans for the purpose of providing information about the diagnosis, prevention, and treatment of disease or impairment in or assessment of health. The CLIA program is user-fee funded; therefore, all costs of administering the program must be covered by the regulated facilities. CLIA requires that all entities that perform even one test, including waived tests, must meet certain federal requirements and must register as a laboratory. An application must be submitted that reports information about a laboratory’s operation. The type of certificate to be issued and the fees to be assessed are determined from this information.

The CLIA categorization of commercially marketed in vitro diagnostic tests is now the responsibility of the U.S. Food and Drug Administration (FDA). The FDA has assumed primary responsibility for performing the CLIA complexity categorization functions, which include the process of assigning commercially marketed in vitro diagnostic test systems to one of three CLIA regulatory categories on the basis of their potential risk to public health: waived tests, moderate-complexity tests, and high-complexity tests.

Urinalysis

Urinalysis includes the physical, chemical, and microscopic examination of urine. In the physical examination, the color, clarity, and specific gravity are noted. Chemical analysis is performed to measure levels of such analytes as glucose, protein, ketones, blood, bilirubin, urobilinogen, nitrites, and pH. Microscopically the urine is examined for the presence of red, white, and epithelial cells, mucus, casts, crystals, yeasts, parasites, and bacteria. Additional quantitative tests may be performed in the urinalysis department to confirm routine screening tests.

Hematology

Tests performed in the hematology division may be qualitative or quantitative. Blood cell counts determine the exact number of RBCs or erythrocytes, white blood cells (WBCs, or leukocytes), or platelets (thrombocytes) either by manual or automated counting. Qualitative tests determine the characteristics of cells, such as size, shape, and maturity. In addition, the hematology department performs tests to determine the coagulating ability of blood components.

Chemistry

The clinical chemistry department analyzes blood, cerebrospinal fluid (CSF), urine, and joint fluid (synovial fluid). Procedures may include single tests or profiles, which include tests for a number of related analytes. Lipid profiles, for example, include assessments of total cholesterol, triglycerides, and low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol.

Microbiology

Microbiology involves the study of bacteria, fungi, yeasts, parasites, and viruses. In the microbiology laboratory, microorganisms are grown (cultured) from blood, urine, sputum, CSF, and wound specimens and are identified. Sensitivity testing then is performed on these organisms to determine the proper antibiotic therapy. Specimens for microbiology must be collected aseptically in sterile containers.

Safety Standards and Governing Agencies

Safety standards for laboratories are initiated, regulated, and reviewed by several agencies or committees. These include the U.S. Department of Labor’s Occupational Safety and Health Administration (OSHA); the Clinical and Laboratory Standards Institute (CLSI, formerly the National Committee for Clinical Laboratory Standards), a nonprofit educational organization that provides a forum for the development, promotion, and use of national and international standards; the CDC, an agency of the U.S. Department of Health and Human Services; the College of American Pathologists (CAP), a leader in providing laboratory quality improvement programs; and the Environmental Protection Agency (EPA), a government agency charged with protecting human health and safeguarding the natural environment.

Physical Hazards

Physical hazards in the laboratory can be classified as electrical, fire, and mechanical hazards. Electric shock is a threat when any electrical equipment is in use. It is imperative to keep all electrical equipment in proper repair and always to follow manufacturers’ instructions.

Open flames are rarely used in a laboratory, but the potential for fire still exists. Fires may be ignited by smoking, heating elements, and sparks. Flammable materials should not be stored near any source of ignition. All laboratory personnel should be familiar with the locations of fire extinguishers and fire safety blankets. Fire extinguishers should be the carbon dioxide (CO₂), dry chemical, or halon type, known as the ABC type of extinguisher. ABC extinguishers can be used on all types of fires. These extinguishers should be inspected regularly by a licensed inspector and replaced or recharged if used. The medical assistant may be responsible for maintaining records on the care and maintenance of fire extinguishers.

Fire safety blankets should be used to smother flames on burning clothing. However, a victim should not be wrapped in a fire blanket, because this may intensify burns. Instead, the flames should be patted out or the victim directed to roll on the blanket.

Emergency phone numbers should be posted on the wall near the telephone, and all personnel should know the locations of fire alarms, the fire escape routes, and procedures to follow if exits are blocked. Periodic fire drills should be conducted, and hallways and exits should be kept free of clutter.

Mechanical hazards arise from the use of laboratory equipment. Special care should be exercised when using equipment with moving parts, such as centrifuges, and those that rely on pressure, including autoclaves. Centrifuges, devices that separate liquids from solids, present a hazard not only from moving parts but also from glassware that might break during centrifugation and from aerosols that might be created if tubes are not capped tightly. Pressurized types of equipment, such as autoclaves used in sterilization, present a danger if opened prematurely. Although centrifuges and autoclaves often have built-in safeguards, such as locks that prevent entry until the environment is safe, improper care of the equipment can result in failure of the safety measures.

Chemical Hazards

The clinical laboratory is home to chemicals that are flammable, caustic, poisonous, carcinogenic, and/or teratogenic. Exposure to these dangerous chemicals can occur through inhalation, direct absorption through the skin, ingestion, entry through a mucous membrane, or entry through a break in the skin. OSHA is involved in regulating the standards directed at minimizing occupational exposure to hazardous chemicals in laboratories. The OSHA hazard communication standard (known as the employee “right to know” rule) became law in 1991 and ensures that laboratory workers are fully aware of the hazards associated with their workplace. The law requires the development of a comprehensive plan to implement safe practice throughout the laboratory with regard to chemicals. This chemical hygiene plan must outline the specific work practices and procedures needed to protect workers from any health hazards that may arise from working with in-stock chemicals. All workers must be provided with information and training, and a material safety data sheet (MSDS) must be on file for all chemicals used in the laboratory. OSHA requires the manufacturer of the chemical to make these sheets available, usually as a package insert.