Comprehensive Study Notes on Clinical Laboratory Science

Vocabulary

  • Cytology (sie TOL oh jee): The study of cells using microscopic methods.

  • Exudates (EKS yoo dayts): Fluids with high concentrations of protein and cellular debris that have escaped from the blood vessels and have been deposited in tissues or on tissue surfaces.

  • Forensic (fuh REN sik): Scientific tests or techniques used regarding the detection of crimes.

  • Hemolyzed (HEE muh liezd): A blood sample in which the red blood cells have ruptured.

  • Histology (hi STOL oh jee): The study of tissues.

  • Inhalant (in HAY lunt): Any substance that can be breathed into the lungs.

  • International Normalized Ratio (INR): Also called prothrombin time (PT). Used to test the effectiveness of blood-thinning medication.

  • In vitro: Latin term meaning "in glass" and commonly known as "in the laboratory."

  • Pathologist (pah THOL uh jist): A physician specially trained in the nature and cause of disease.

  • Pure culture: The growth of only one microorganism in a culture or on a nutrient surface.

  • Quality assurance: Written policies and procedures that ensure monitoring of all processes involved before, during, and after testing.

  • Reagent (re AY jent): A substance used in a chemical reaction.

  • Referral laboratory: A laboratory that performs testing for another laboratory. The testing varies from high-volume routine testing to low-volume unique or unusual testing. Also called reference, diagnostic, or commercial testing laboratories. Often privately owned.

  • Sharps: Medical term for devices with sharp points or edges that can puncture or cut skin. Examples include needles, scalpels, or broken glass.

  • Specimen: A biological sample such as blood, urine, body fluids, feces, or tissue collected for analysis and evaluation.

  • Standard operating procedures (SOP): A set of step-by-step instructions to help employees carry out routine operations with efficiency, high quality, and uniformity of performance.

  • STAT: The medical abbreviation for the Latin term "statum," meaning immediately; at this moment.

  • Sterile: Free from all living organisms.

  • Toxicology (tok si KOL oh jee): The study and science that deal with the effects, antidotes, and detection of poisons or drugs.

Introduction

Laboratory medicine is the medical discipline that applies clinical laboratory science to the care and diagnosis of patients. Laboratory tests are used for four main purposes:

  1. To document the good health of a patient.

  2. To screen patients for diseases and conditions such as diabetes, high cholesterol, or urinary tract infections (UTIs).

  3. To help the provider diagnose a medical disease, disorder, or condition.

  4. To help the provider decide on the most appropriate treatment, monitor the effects of medications and treatments, and monitor a disease process.

Healthcare providers order laboratory testing for patients. Patient specimens are collected at the laboratory, an ambulatory care facility, or home. A specimen is defined as a sample of body fluid, waste product, or tissue collected for analysis. Once in the laboratory, specimens are processed and directed to the proper laboratory department. Each department of the lab analyzes and evaluates the specimen based on specific tests ordered by the provider. Tests can be performed manually (by hand) or through various specialized automated instruments. Once test results are completed, they are reported back to the provider.

Role of Medical Assistants

When healthcare providers order laboratory tests for patients, medical assistants can enter the provider's order into the laboratory ordering system. The responsibilities of the medical assistant may include:

  • Providing the patient with specimen collection instructions.

  • Collecting and labeling patient specimens.

  • Assisting with preparing specimens to be transported to a laboratory for testing.

  • Performing CLIA-waived testing.

The medical assistant must be knowledgeable about patient preparations, testing procedures, and the normal range of results for common tests. They must carefully follow all laboratory instructions and communicate effectively with team members and patients to ensure patient comfort and cooperation during procedures.

Organization of the Clinical Laboratory

Certain components are found in all clinical laboratories, including personnel, tests, and departmental organization. The following discussions delve into these aspects.

Personnel in the Clinical Laboratory

Medical laboratories are found in hospitals, ambulatory care facilities, public health departments, health maintenance organizations, and referral laboratories (also known as reference laboratories). The clinical laboratory is staffed with various professionals, including:

  • Director: This may be a pathologist or a clinical laboratory scientist with a doctorate degree. In ambulatory care facilities, the lab director may be the physician, referred to as a physician's office laboratory (POL).

Certification Agencies and Positions

Certifying agencies and their respective titles are as follows:

  • American Society for Clinical Pathologists (ASCP):

    • MLS (ASCP): Medical laboratory scientist

    • MT (ASCP): Medical technologist

    • MLT (ASCP): Medical laboratory technician

    • MLT-AD (ASCP): Medical laboratory technician-associate degree

    • CMLA (AMT): Certified medical laboratory assistant

  • American Medical Technologists (AMT):

    • RPT: Registered phlebotomy technician

    • RMA: Registered medical assistant

    • CMA (AAMA): Certified medical assistant

  • National Healthcareer Association (NHA): Clinical laboratory scientists (CLSS) and clinical laboratory technicians (CLTS).

Medical assistants (CMAs, RMAs, CCMAs) are trained to collect patient specimens properly and perform specific testing procedures within the POL. They are also trained to collect specimens for testing at reference laboratories.

Clinical Laboratory Testing

Clinical laboratory testing is performed alongside a thorough health history and physical examination to gather essential data for management. The body maintains a healthy state known as homeostasis, where physical and chemical characteristics of body substances fall within an acceptable range (normal range or reference range). The normal range reflects numeric test values observed consistently in the general population 95% of the time. Changes in internal body environments can lead to abnormal test values outside the reference range.

When laboratory tests are used for diagnosis, patient results are compared against the reference range.

Importance of Reference Ranges

Reference values are beneficial in assessing patient treatment progress. Medical institutions establish their own reference ranges, which medical assistants must be familiar with. Abnormal test values can correlate with multiple pathologic conditions, highlighting the necessity for providers to utilize a combination of results from the patient’s history, physical examination, and various diagnostic and laboratory tests when making diagnoses.

Types of Clinical Laboratory Tests

Clinical laboratory tests can vary from simple screening tests measuring one analyte to complex profile testing involving multiple analytes. Screening tests check for the presence of an analyte that might indicate a disease state, but they are not definitive for a single disease. Such tests are generally performed according to age, history, or gender of patients.

Types of Test Results

Clinical laboratory tests can be reported in three formats:

  1. Qualitative: Results are categorized as positive or negative without numeric values. Example: A CLIA-waived mononucleosis test.

  2. Semi-quantitative: Results are estimates rather than specific amounts. Example: Reported as trace amounts or graded as 1+, 2+, or 3+.

  3. Quantitative: Results expressed as numeric values, often with attached units of measurement. Example: A blood glucose test reported as 120 mg/dL, where mg/dL indicates milligrams per deciliter.

Critical Thinking Application

As an exercise, consider how to define qualitative, semi-quantitative, and quantitative test results eloquently in your own words.

Departments of the Clinical Laboratory

Larger laboratories are divided into various departments, including:

  • Urinalysis

  • Hematology

  • Chemistry

  • Microbiology

  • Specimen collection and processing

  • Blood bank (immunohematology)

  • Coagulation

  • Immunology/serology

  • Histology

  • Cytology

  • Toxicology

  • Special chemistry

Some larger laboratories adopt a core laboratory concept, combining clinical hematology, immunochemistry, chemistry, toxicology, and coagulation for efficient processing.

Urinalysis

Urinalysis involves a thorough examination (physical, chemical, and microscopic) of urine. The color, clarity, specific gravity, and temperature (to confirm freshness) are noted. Several analytes are tested using a multiple test strip or dipstick, including glucose, protein, and pH. Urinalysis will be elaborated upon further in Chapter 47.

Microscopically, urine is examined for elements such as red and white blood cells, epithelial cells, and various crystals or microorganisms.

Hematology

The hematology department studies blood cells and coagulation. It performs both qualitative and quantitative tests, such as hemoglobin and hematocrit testing, in the POL setting. Reference labs perform blood counts to assess various cell types, while microscopic evaluations provide insights into cellular characteristics.

Chemistry

The clinical chemistry department analyzes chemicals in various fluids. Manual or automated testing procedures are employed for single analyte or multitest profiles, such as lipid profiles measuring cholesterol types. Emerging compact technology facilitates chemistry testing in ambulatory care.

Microbiology

Microbiology explores small infectious organisms, utilizing specimens like blood, urine, and stools for analysis. Specimens must be aseptically collected to avoid contamination. Goals include identifying the causative pathogens and determining effective antimicrobial treatments through identification and sensitivity testing when needed. Progress in microbial testing technologies continues to change how identification is conducted.

Examples from Microbiology Testing

  • Rapid strep testing may be conducted for streptococcal throat infections.

  • Specimens may be prepared and sent to reference labs for advanced testing.

Government Legislation Affecting Clinical Laboratory Testing

In 1988, Congress enacted the Clinical Laboratory Improvement Amendments (CLIA), which established quality standards for clinical laboratory testing. CLIA ensures accuracy, precision, reliability, and timeliness of patient test results regardless of the lab performing the tests. Any facility conducting laboratory testing on human specimens must comply with federal requirements and register with the Centers for Medicare and Medicaid Services (CMS).

Categories of CLIA Testing

  1. CLIA-waved Tests: These are simple laboratory tests with minimal risk of incorrect results, typically approved for home use. Examples include rapid drug tests and certain pregnancy tests.

  2. Moderate-complexity Tests: Examples include hematology and some microbiology procedures. These require qualified personnel to conduct.

  3. High-complexity Tests: Typically do not occur in POLs but are instead carried out in hospital or reference labs. They need stringent CLIA regulations and carry higher risk and complexity.

Within laboratories, quality assurance (QA) ensures monitoring of processes for reliable patient test results. QA involves comparing documented processes against actual practices.

The Three Stages of Quality Assurance in the Laboratory

Quality assurance is divided into three stages:

1. Preanalytic Stage

  • The test order is given and documented.

  • Specimen collection, labeling, and transport occur.

2. Analytic Stage

  • Instruments are maintained and calibrated.

  • Tests are performed, and results documented.

3. Postanalytic Stage

  • Proper disposal of specimens and release of results occur.