1. To screen patients for possible disorders. Screening test results are used to determine if a disease or medical condition exists in patients who may not have signs or symptoms of an underlying disease process. These tests are becoming increasingly popular because they can detect potential chronic disorders (long-lasting, debilitating conditions) such as coronary heart disease and diabetes well before irreversible damage sets in. Primary care physician offices and community health centers are encouraged by the latest Medicare policies to participate in screening programs. The workbook has a health screening report form that includes the various screening tests that will be presented throughout the text and in the laboratory sessions.

2. To establish a diagnosis. Diagnostic test results help identify or confirm a disease or medical condition. These results can significantly affect the medical care and treatment of the patient. Diagnostic tests should be run by well-trained individuals and must correlate with other clinical findings (e.g., the patient’s medical history and physical examination).

3. To monitor the patient’s condition or treatment. Monitoring test results helps the physician keep track of the patient’s specific medical condition or response to treatment on a periodic basis. The following three medical conditions commonly require routine testing to monitor the effects of medication treatments:

• Patients at risk of heart disease who are taking cholesterol-lowering medications are checked periodically for cholesterol levels and liver enzymes. The medication goal is to bring cholesterol levels below 200 and to determine whether the medication is harming the liver, which would raise the blood enzymes ALT and AST (this will be covered in Chapter 6). They may also be tested for C reactive protein (CRP), which is associated with myocardial infarction (heart attack) and indicates the health status of the patient’s cardiovascular system.

• Patients at risk of forming internal clots (thrombosis) who are taking anticoagulant medications are checked to see if their blood coagulation (clotting) time is too fast or too slow.

• Patients with diabetes have their blood sugar levels checked periodically at the office. They also may have their self-monitored blood sugar results interpreted by the physician. In both cases the physician needs to determine if these patients are maintaining blood sugar levels within the recommended reference range (the range of analyte values with which the general population will consistently show similar results).

1. Measuring the levels of analytes compared with reference values. The human body is a remarkable organism, capable of maintaining homeostasis (a steady state of internal chemical and physical balance). This universal ability is seen when a healthy population is tested for the presence of a particular analyte (a substance being tested, such as the level of glucose or cholesterol in a blood specimen). Most of the population will test within a range of similar results. This is referred to as the reference range for that analyte. When disease strikes, a person’s homeostatic balance is disrupted, causing the analyte results to fall outside the reference range.

The following is an example of the information that can be obtained by monitoring the level of a patient’s glucose (sugar) analyte and comparing it to its established population’s reference range. A physician obtained a variety of abnormal clinical signs and symptoms when examining a female patient—rapid weight loss, lack of energy, polyphagia (excessive hunger), polydipsia (excessive thirst), and polyuria (excessive urination). These symptoms caused the physician to suspect the disease diabetes mellitus (a disease caused by the lack of insulin or the inability to regulate blood sugar levels). The physician then ordered a blood glucose test and received a result of 300 mg/dL (milligrams per deciliter). The population’s reference range for blood glucose levels was 70 to 110 mg/dL. The patient’s extremely high glucose result, along with all the other signs and symptoms, indicated that her pancreas was unable to produce the insulin necessary to regulate glucose in a homeostatic way. A repeat fasting blood glucose test showed the same high result that confirmed the diagnosis of diabetes. The physician then prescribed a course of treatment and continued to monitor the blood glucose levels until the patient’s test results returned to the proper reference range.

Fig. 1-1 is an example of a reference laboratory’s comprehensive report for blood tests. Note that the reference range for each analyte tested is listed above the patient’s test value. If a test result is far from the reference range, it may be referred to as a critical value or panic value (indicating a threat to a patient’s health). The laboratory report must mark or highlight the critical result requiring immediate attention. In the figure, Judith Johnson does not have any critical values. A variety of laboratory reports (results of laboratory tests that have been ordered) are shown and discussed throughout this text.

2. Observing and detecting abnormal cells under the microscope. Another way to analyze a specimen is to search for abnormal cells or pathogens (disease-causing microorganisms) under the microscope. In the ambulatory setting this form of testing is generally limited to basic identification of abnormal cells and microorganisms found in urine, blood, or samples taken from infected tissues. Fig. 1-2 shows the abnormal presence of red blood cells and yeast cells in a urine specimen.

This book discusses some of the normal and abnormal microscopic findings in urine, blood, and microbiology specimens to highlight their significance. Additional training beyond this text is required to identify and report microscopic findings.

3. Detecting the presence or absence of an infection. The third way to analyze specimens is to test for the presence of pathogens causing an infection. In the ambulatory setting increasing numbers of rapid screening tests are available to help the physician identify the presence of common pathogens. For example, test kits (all components of a test packaged together) are available that can detect the presence of bacteria that cause strep throat, peptic ulcers, and Lyme disease as well as the viruses that cause influenza, mononucleosis, and AIDS. Note the Rapid Strep test results from two throat-swabbed specimens in Fig. 1-3. The left test result is negative for streptococcus A, and the right test is positive for streptococcus A. Further microscopic, chemical, and growth analysis of the pathogen, along with analysis of the pathogen’s sensitivity to antibiotics, is performed by sending the infected swabbed specimen to a microbiology laboratory.

• Pathologists are physicians with doctorate degrees who have specialized in test methodology and the diagnosis of diseases.

• Clinical laboratory scientists and medical technologists have master’s and bachelor’s degrees, are specialists in laboratory testing, and have received one of the following nationally recognized credentials: MT (ASCP), MT (AMT), CLS (NCA), RMT (ISCLT), or CLT.

• Medical technicians have 2-year associate degrees in laboratory training and have received one of the following nationally recognized credentials: MLT (ASCP), MLT (AMT), CLT (NCA), or RLT (ISCLT).

• Routine urinalysis and pregnancy testing

• Basic hematology tests—hemoglobin, hematocrit, sedimentation rate

• Coagulation—prothrombin time and its computed international normalized ratio result

• Chemistry—glucose, hemoglobin A1c, lipid panel, alanine aminotransferase (ALT) and aspartate aminotransferase (AST), electrolytes, and BUN

• Immunology/serology—mononucleosis test, Helicobacter pylori test, OraQuick test for HIV

The physician’s office laboratory (POL) has greatly benefited and will continue to benefit from the technical advancements that have improved and simplified so many medical testing methods. A major benefit of POL testing is that ambulatory patients can now obtain their screening and monitoring test results immediately rather than needing to drive to an external laboratory. Also, the physician’s interpretation and therapeutic recommendations can now be given during the same office visit. This has led to better patient care and patient compliance (a patient’s willingness to follow a treatment plan and take an active role in his or her own health care). Many physicians may also perform basic microscopic procedures that have been CLIA approved. NOTE: The CLIA-waived approval process and basic microscopy will be presented in Chapter 2.

Reference and hospital laboratories will continue to provide physicians with the results of the more complex tests. Patient specimens must be sent to these laboratories for the critical test results that provide the doctor with sufficient information to make definitive diagnoses. Because of the complexity of these diagnostic tests, they must be performed by individuals with extensive laboratory training, education, and credentialing. A complete description of such knowledge and training is beyond the scope of this book.

Physician office laboratories are generally staffed by physicians, physician assistants, nurse practitioners, and medical assistants. Medical assistants are multiskilled professionals who assist in the patient-care management in medical offices, clinics, and ambulatory care centers. They perform administrative duties and clinical procedures, including the basic CLIA-waived laboratory tests. Medical assistants attend a 1- or 2-year program and are nationally credentialed as CMA (AAMA) or RMA (AMT). There may also be trained laboratory technicians working in the larger POLs that service multiple physicians.

Table 1-1 lists all the health care professionals involved in medical laboratory testing. They are organized by educational credentials, from doctorates to associate degrees and to technical certification. (Nurses are not listed because laboratory training is not part of their education. They are often trained on the job in physicians’ offices.)

TABLE 1-1

Personnel Involved in Laboratory Testing

Title	Credential	Years of College Training and Degree	Laboratory Setting
Board-certified pathologists	MD or DO	8 or more: doctorate	Reference and hospital laboratories
Primary care physicians and specialists	MD or DO or ND (naturopathic doctor)	6 or more: doctorate	Physician’s office laboratory and health clinics
Physician assistants and nurse practitioners	PA, NP	6 or more: master’s	Physician’s office laboratory and health clinics
Clinical laboratory scientist, National Certification Agency for Medical Laboratory Personnel	CLS (NCA)	4 or more: bachelor’s or master’s	Reference and hospital laboratories
Medical technologist, American Society of Clinical Pathologists	MT (ASCP)	4 or more: bachelor’s	Reference and hospital laboratories
Medical technologist, American Medical Technologists	MT (AMT)	4 or more: bachelor’s	Reference and hospital laboratories
Registered medical technologist, International Society for Clinical Laboratory Technology	RMT (ISCLT)	4 or more: bachelor’s	Reference and hospital laboratories
Clinical laboratory technologist, Department of Health and Human Services	CLT (HHS)	4 or more: bachelor’s	Reference and hospital laboratories
Medical laboratory technician, American Society of Clinical Pathologists	MLT (ASCP) ∗	2: associate degree	Reference and hospital laboratories and physician’s office laboratories
Medical laboratory technician, American Medical Technologists	MLT (AMT) ∗	2: associate degree	Reference and hospital laboratories and physician’s office laboratories
Clinical laboratory technician, National Certification Agency for Medical Laboratory Personnel	CLT (NCA) ∗	2: associate degree	Reference and hospital laboratories and physician’s office laboratories
Registered laboratory technician, International Society for Clinical Laboratory Technology	RLT (ISCLT) ∗	2: associate degree	Reference and hospital laboratories and physician’s office laboratories
Registered phlebotomist	National certification ∗	1: technical certificate	All laboratories
Certified medical assistant, American Association of Medical Assistants and CAAHEP	CMA (AAMA) ∗	1: associate degree or 2: technical certificate	Physician’s office laboratory and ambulatory settings
Registered medical assistant, American Medical Technologists	RMA (AMT) ∗	1: associate degree or 2: technical certificate	Physician’s office laboratory and ambulatory settings

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