Introduction

A wide variety of blood tests are covered in this text, ranging from the basic blood cell tests that count and measure blood cell number and size, to the more complex and diagnostically significant blood chemistry tests in subsequent chapters. This chapter focuses on blood cell tests that identify variations in the number of blood cells, describes the function of certain blood cells, and identifies diagnoses related to variations in the number of blood cells. In addition, this chapter includes...

Key Terms Abbreviations and Acronyms

Antistreptolysin O titer, ASO complement fixation (CF) test Coombs' test direct fluorescent antibody, DFA enzyme immunoassay, EIA enzyme-linked immunosorbent assay, ELISA fluorescent treponemal antibody absorption (FTA-ABS) test hemagglutination inhibition (HAI) test human immunodeficiency virus type 1 (HIV-1) human immunodeficiency virus type 2 (HIV-2) indirect (reverse) ABO blood grouping indirect fluorescent antibody, IFA infectious mononucleosis, IM latex agglutination...

Summary

Effusions are excessive accumulations of fluid in various body cavities that are classified as transudates and exudates. Pericardial effusions, pleural effusions, peritoneal effusions, and synovial effusions are withdrawn by way of pericardiocentesis, thoracentesis, paracentesis, and arthrocentesis, respectively. Pericardial effusion analysis assists in diagnosing pericarditis, aneurysms, tuberculosis, Dressler's syndrome, and malignancies. Peritonitis, pancreatitis, ruptured gallbladder, and...

Brain Scan

A brain scan is a radionuclide study of the brain that assesses brain structure, function, and the integrity of the blood-brain barrier. The blood-brain barrier is a protective barrier of brain tissues that prevents the movement of substances from the blood to the brain. The radionuclide is administered intravenously and should not cross the blood-brain barrier. Abnormalities or diseases of the brain may prevent the blood-brain barrier from functioning properly and permit the radionuclide to...

Esophagogastroduodenoscopy EGD

Esophagogastroduodenoscopy (EGD) involves direct visualization of the esophagus, stomach, and duodenum through the use of a flexible scope. This procedure may be called esophagogastroscopy, esophagoscopy, gas-troscopy, or duodenoscopy, depending upon the structures or combination of structures being examined. The EGD allows the physician to examine the mucosa of the upper gastrointestinal tract from the esophagus to the middle of the duodenum. This endoscopic procedure serves many diagnostic...

Thoracoscopy

Thoracoscopy is an endoscopic procedure that is used to examine the thoracic cavity and allows the physician to visualize the thoracic walls, pleura, pleural spaces, pericardium, and mediastinum. This is one of the more complex endoscopic examinations, is a surgical intervention, and requires the administration of local or general anesthesia. The endoscope is passed into the thoracic cavity by way of a small incision made in the chest wall. During the exam the lung at the site of the procedure...

Bilirubin

Bilirubin is a waste product resulting from the lysis of red blood cells and the release of hemoglobin. The heme (iron) portion of the hemoglobin molecule is converted into the bile pigment bilirubin. Bilirubin is a yellow pigment. An abnormally increased blood concentration creates a jaundiced discoloration of the skin, whites of the eyes, and mucous membranes. Bilirubin is eliminated from the body through a complex process involving the liver. There are two main forms of bilirubin indirect or...

Head and Brain Magnetic Resonance Imaging

Magnetic resonance imaging of the head and brain provides information about the blood flow to the face, head, and brain. Structure and tissue abnormalities of the nasopharynx, neck, and tongue are also identified. Figure 10-6 is a an example of an MRI of the head and brain. Figure 10-6. MRI of the brain and head Normal Findings. Normal structure of the head and brain. Absence of pathology. Variations from Normal. Head and brain magnetic resonance imaging reveals brain tumors, both primary and...

Overview of Ultrasound Procedures

Ultrasonography is a safe, noninvasive procedure that uses sound waves to create images of the soft tissues of the human body. A transducer is used to direct sound waves into the body. The skin over the area being studied is coated with conductive gel or lotion, and the transducer is pressed lightly against the skin. Once the sound waves reach the underlying body structures, they bounce back to the transducer that converts the returning sound waves into electrical signals. The electrical...

Coccidioidomycosis

Coccidioidomycosis, also known as valley fever, San Joaquin fever, and desert fever, is an infectious disease caused by inhaling the spores of the fungus Coccidioides immitis. The primary infection may be entirely asymptomatic, or may resemble an acute influenza illness or a common cold. Diagnosis is made by microscopic examination or culture of sputum, pus, urine, or cerebrospinal fluid. Serologic tests for coccidioides antibodies include complement fixation and immunodiffusion. These tests...

Case Studies

Edgar Raymond, a 46-year-old coal miner with chronic lung congestion, has been scheduled for a bronchoscopy by Dr. Sullivan. Discuss the purpose of a bronchoscopy and how it is performed. What diseases might be found with this endoscopic procedure Mr. Raymond experienced a pneumothorax during the procedure. Is this normal If so, why 2. Sheila Middlebrook, a 56-year-old-woman with a history of alcoholism, has symptoms of abdominal pain and ascites. Dr. Hart has decided that a laparoscopy must be...

Electromyography EMG

Electromyography (EMG) is an invasive diagnostic test that is used to detect a variety of primary and secondary muscular disorders. Primary muscular diseases are a result of problems with the muscle tissue itself, whereas secondary muscular disorders are associated with other disease processes such as nerve dysfunction. Contraindications for EMG include anticoagulant therapy and infection at or near the sites of electrode placement. EMG is often done in conjunction with electroneurography,...

Diseases of Fungal Origin

Fungi are defined as thallus-forming organisms, with defined nuclei, which require an external carbon source. Fungus may invade living as well as nonliving organisms. Most fungi are found in the soil and on decaying plant matter. Of the 250,000 known fungal species, less that 200 are considered capable of causing disease. Deep-seated and opportunistic fungal diseases are more common in individuals who are immunosup-pressed. Most pathogenic fungi stimulate antibody formation. Serologic tests for...

Cardiovascular System

Abdominal Aortic Ultrasonography Angiography Arteriography of the Lower Extremities Aspartate Aminotransferase Chest X-ray Coronary Angiography Creatine Kinase Digital Subtraction Angiography Echocardiography Electrocardiography Electrophysiology Study Exercise Stress Test High-Density Lipoprotein Holter Monitor Test Intravascular Ultrasonography Low-Density Lipoprotein Multigated Acquisition Scan Myocardial Infarction Scan Pericardial Effusion Test Radionuclide Scan of the Chest...

Kidney Scan

Kidney scans, also called renal scans, are radionuclide studies of the size, shape, and function of the kidney. The kidney scan may be done to evaluate renal structure, function, and blood flow renal excretory function and glomerular filtration rates. The type of information obtained from the scan varies according to the purpose of the scan and the radionuclide used. Specific kidney structures are sensitive to different radionuclides. For example, one radionuclide may be used to scan the...

Bladder Ultrasonography

In addition to evaluating bladder size, shape, structure, position, and function, bladder ultrasonography is used to identify tumors, masses, and obstruction of the urinary tract. Masses or tumors pressing against the bladder wall can be detected as changes in the shape or position of the bladder. This ultrasound test is also used to measure the amount of residual urine remaining in the bladder after the patient has voided. A large residual urine volume may be indicative of an obstruction of...

Chapter Review

Identify the following special organ studies a. Evaluates the auditory pathways of the brain stem b. Evaluates the ability of the alveoli and capillaries to exchange gas c. Measures and records the electrical activity of the brain d. Invasive diagnostic study of the conduction system of the heart e. Measures and records brain wave activity produced by stimulation of a pathway f. Measures arterial blood oxygen saturation g. Identifies the potential risk for ventricular dysrhythmias in...

Legionnaires Disease Tests

Legionnaires' disease, also known as legionellosis and Legionnaires' pneumonia, is an acute bacterial disease that attacks the respiratory system. The causative bacteria are Legionella pneumonophila. Hot-water systems, cooling towers, humidifiers, whirlpool spas, and respiratory therapy devices have been identified as containing or housing these bacteria. The mode of transmission is airborne. Legionnaires' disease can be diagnosed by blood, sputum, or pleural fluid cultures. However, the most...

Diseases of Viral Origin

Viruses are defined as minute microorganisms that can only replicate by invading a living cell. Figure 5-2 demonstrates the relative size of different viruses. All viruses consist of a nucleic acid core, either deoxyribonucleic acid (DNA) or ribonucleic acid (RNA), and an antigenic protein coat. Some viruses have an additional layer called an envelope, which is a lipoprotein. The virus provides the genetic code for replication and the cell provides the needed energy and raw materials. As the...

Gastric Secretion Tests

Few to none present Few to none present Few to none present Variations from Normal. A change in the color of gastric secretions must be evaluated in conjunction with other test results. A yellow to green color can indicate bile reflux or an obstruction in the small intestine. The presence of large amounts of blood, or blood that has the appearance of coffee grounds, is consistent with ulcers, gastritis, or cancer. Variations in the pH of gastric secretions is seen in aplastic, hyperchromic, and...

Histoplasmosis

Histoplasmosis, a systemic infection caused by inhaling the spores of the fungus Histoplasma capsulatum, is characterized by fever, malaise, cough, and lymphadenopathy. The lungs and respiratory structures are the usual sites of primary lesions. Diagnosis can be confirmed by culture or actual visualization of the fungus. Serologic antibody tests used to diagnose histoplasmosis include complement fixation, latex agglutination, and immunodiffusion. The immunodiffusion test has been identified as...

Antigen Antibody Reaction

The antigen-antibody reaction is part of the body's natural defense mechanism. An antigen, also called an immunogen, is any substance that stimulates the formation of specific antibodies and reacts with those specific antibodies. Antigens may enter the body by way of the bloodstream, through breaks in the integrity of the skin, and by infiltrating the respiratory and gastrointestinal tract. An antibody, also called an immunoglobulin, is a substance that appears as the result of the introduction...

Kidney Ultrasonography

Kidney ultrasonography, also called renal ultrasonography, is an ultrasound examination of the kidney that is performed to asses the kidney size, structure, and position and to diagnose and monitor various renal disorders. Urinary blockage and abnormal fluid or blood accumulation in the kidney is also assessed via kidney ultrasound. With the patient in the supine or side-lying position, the area over the kidney is exposed, conductive gel is applied, and the transducer is moved across the area....

Angiography

Angiography is a generic term used to describe x-ray examinations of the vascular system. Blood and lymph vessels are studied by injecting a contrast medium, usually iodine, into the femoral artery, the brachial artery, or other veins and arteries. A catheter is placed into the artery or vein, the contrast medium is injected, and the x-rays are taken. When satisfactory films have been obtained, the catheter is removed, pressure is applied to the puncture site, and the patient must remain at...

Antidiuretic Hormone ADH

Antidiuretic hormone (ADH) is manufactured by the hypothalamus, secreted by the posterior lobe of the pituitary gland, and controls the amount of water reabsorbed by the kidneys. An increase in serum osmotic pressure or a decrease in blood volume triggers ADH release. Circulating ADH targets kidney cells and more water is reabsorbed, thereby increasing blood volume. Antidiuretic hormone is also known as vasopressin because it causes constriction of arterioles, which in turn raises blood...

Aspartate Aminotransferase AST Serum Glutamic Oxaloacetic Transaminase SGOT

Aspartate aminotransferase (AST), also known as serum glutamic-oxaloacetic transaminase (SGOT), is an enzyme found in tissues and cells where there is high metabolic activity. Very high concentrations are present in heart muscle, liver cells, and skeletal muscle cells. Lesser but noteworthy concentrations are also in the kidneys, pancreas, brain, spleen, and lungs. Aspartate aminotransferase is released into the bloodstream by virtue of cell injury or death. The AST enzyme is one of the...

Learning Objectives

Upon completion of this chapter, the learner should be able to 1. Briefly describe the purpose and structures examined for each radiography study. 2. Discuss the indications and contraindications for each radiography study. 3. Properly sequence radiography examinations. 4. Relate specific diagnoses to specific radiographic studies. 5. Organize radiography studies in relation to whether or not contrast media are necessary. 6. Compare the benefits and risks of computerized axial tomography,...

Labeled Immunoassays

Antigen-antibody reactions are for the most part invisible both microscopically and to the naked eye. When the antigen is not large enough to be visualized, the antigen must be bound to a larger particle so that the antigen-antibody reaction can be visualized. Agglutination or precipitation are good examples of visible antigen-antibody reactions. Labeled immunoassays are laboratory tests to detect an antigen-antibody reaction by using labels attached either to the antigen or the antibody. The...

Gallbladder Ultrasonography

Gallbladder ultrasonography is an ultrasound examination of the gallbladder and the bile ducts that is performed to assess the size, shape, and position of the gallbladder and biliary ducts. Identification of gallstones, abnormalities, and inflammation can be accomplished with this sonogram. If the liver is evaluated at the same time, the examination is called hepatobiliary ultrasonography. Gallbladder ultrasonography may be used to guide the physician in the process of obtaining a biopsy or...

Endoscopic Studies of the Abdominal Cavity

Endoscopic studies of the abdominal cavity include procedures that examine tissues and organs located in the abdominal region of the body. These endoscopic procedures are divided into three categories (1) abdominal endoscopic examination, (2) upper gastrointestinal (GI) tract endoscopies, and (3) examinations of the lower gastrointestinal tract. The laparoscopy, also known as peritoneoscopy, is the overall endoscopic examination of the abdominal organs. It should be noted that the term...

Liver Ultrasonography

Liver ultrasonography is an ultrasound examination of the liver and the hepatic ducts that is performed to assess the size, shape, texture, and position of the liver and hepatic ducts. Hepatic duct patency and diameter can be evaluated via liver ultrasonography. With the patient in the supine position, the abdomen is exposed, conductive gel is applied, and the transducer is moved over the area. Breathing patterns may be altered during the examination. Images are transmitted through the...

Computerized Tomography of the Body Body Scan

Computerized tomography of the body is a radiologic technique that gives detailed cross-sectional images of the chest, abdomen, spine, and extremities. This technique can be used to evaluate blood flow and vascularity of tissue masses. Some areas of the body may need a contrast medium in order to provide clarification of the image. Body CT scans that include the pelvic area may involve the use of a barium contrast or water-soluble enema. Individuals who present with multiple symptoms, and for...

Colposcopy

Colposcopy is the examination of the vagina and cervix by means of a col-poscope, a lighted, binocular microscope. Using the colposcope, the physician is able to visualize the cervix and identify abnormal tissue. The colposcope is fitted with a camera, making it possible to photograph the tissue being examined. Colposcopy makes it possible to detect cancer of the cervix in its early stages, examine tissue from which an abnormal Pap smear has been obtained, and monitor areas of the cervix from...

Preface

Understanding Laboratory and Diagnostic Tests is written and designed to meet the needs of allied health students and professionals who desire a basic understanding of clinical laboratory and diagnostic tests. This textbook presents information about commonly performed tests. The information includes the type of test, that is, blood chemistry, radiographic, urine the body system, organ, or tissue involved in the test the diagnostic significance of the test the purpose or indications for the...

Sweat Test

The sweat test is a noninvasive evaluation that is performed to identify a definitive diagnosis of cystic fibrosis. Cystic fibrosis is an inherited disease that exhibits a variety of symptoms and conditions, including abnormal secretion of sweat. The sweat test is not very reliable during the first few weeks of life or after puberty. Indications for the sweat test include a family history of cystic fibrosis, recurrent respiratory tract infections, malabsorption syndromes, and failure to thrive...

Thyroid Stimulating hormone TSH

Thyroid stimulating hormone (TSH) is secreted by the anterior lobe of the pituitary gland and, as the name implies, stimulates the thyroid gland to produce and secrete thyroxine (T4) and triiodothyronine (T3). Measuring TSH levels is the most sensitive test for identifying and differentiating primary and secondary hypothyroidism. Primary hypothyroidism is a result of thyroid gland malfunction or disease. In secondary hypothyroidism, the thyroid gland is unable to secrete adequate levels of T3...

Skull Radiography

Skull radiography is an examination of the bones of the skull, nasal sinuses, and surrounding structures. Skull x-ray also provides visualization of any cerebral calcifications, particularly of the pineal gland. A calcified pineal gland is a useful marker for locating the midline of the brain. Displacement of this calcification can help identify unilateral hematomas or tumors. Normal Findings. Skull and surrounding structures are normal. Variations from Normal. Skull fractures, metastatic bone...

Fetoscopy

Fetoscopy is an endoscopic examination of the fetus that uses ultrasonography to guide the placement of the fetoscope. The fetoscope is inserted through a small surgical incision into the uterus. Using this procedure the physician is able to examine the physical structure of the fetus and take fetal blood and skin samples. This procedure permits the diagnosis of congenital malformations, blood disorders, and abnormal skin disorders. Fetoscopy is indicated only if there is a high risk of a...

Computerized Axial Tomography Ct Cat Scans

Computerized tomography (CT, CAT) is a radiographic technique that produces a film representing a detailed cross section of tissue structure. Very narrow x-ray beams rotate in a continuous 360-degree motion around the individual to produce cross-sectional images of the body and its structures. Figure 10-5 is an abdominal CT scan. Computerized tomography has been an invaluable addition to the diagnostic tool chest. This technique is able to detect minor differences in the density and composition...

Diseases of Bacterial Origin

Bacteria are defined as small unicellular microorganisms that exhibit metabolic activity and are therefore classified as living organisms. A single organism is a bacterium and the multiplication or growth from a bacterium results in a colony. Bacteria are identified by their morphology or shape as coccus (round), bacillus (rod), spirochete (spiral), and vibrios (comma shaped). Cocci can occur in pairs called diplococci as well as in clusters. Most bacteria do not cause disease and exist as...

Culdoscopy

Culdoscopy is an endoscopic procedure in which the physician is able to visualize the cul-de-sac of Douglas using an endoscope called a culdoscope. The culdoscope is passed through a small surgical incision made into the posterior vagina. This procedure permits the physician to examine the uterus, ovaries, fallopian tubes, pelvic ligaments, rectum, and sigmoid colon. The pelviscopy, which provides better visualization with fewer risks, has replaced the culdoscopy as the procedure of choice when...

Understanding Laboratory and Diagnostic Tests

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Phenylketonuria PKU Urine Test

The phenylketonuria (PKU) urine test is a routine screening test performed on newborns to detect the genetic metabolic disorder known as phenyl- ketonuria. Left untreated, PKU can cause brain damage and mental retardation. PKU is characterized by a lack of an enzyme that converts phenylalanine, an amino acid, to tyrosine, which is required for normal metabolism. PKU urine testing is usually performed during the infant's one-month checkup if earlier blood testing has not been completed. A...

Candidiasis

Candidiasis, an infection caused by Candida albicans, is usually confined to the superficial layers of the skin or mucous membranes. Thrush, diaper rash, intertrigo, and vaginitis are common manifestations of candidiasis. Debilitated patients can present with endocarditis, and infection of the kidney, spleen, liver, bones, eyes, and lungs. Microscopic identification of the yeast cells in infected tissue or body fluids is highly diagnostic. Serologic identification of candidal antibodies is...

Gastrointestinal Reflux Scan

The gastrointestinal reflux scan, also called the gastroesophageal reflux scan, is a radionuclide study of the esophagus and stomach. Indications for this scan are symptoms associated with gastric reflux, which may include heartburn, vomiting, aspiration, regurgitation, or dysphagia. The gastrointestinal reflux scan may encompass scanning the lungs when aspiration of gastric contents presents a concern. In cases of suspected aspiration, the radionuclide is administered with the evening meal....

Triiodothyronine T3

Triiodothyronine (T3) is another hormone secreted by the follicular cells of the thyroid gland and appears to have the same functions as thyroxine. Although triiodothyronine accounts for a very small percentage of thyroid hormone secretions, it is very concentrated and highly potent. As with thyroxine, triiodothyronine plays an important part in many cellular and metabolic processes. The serum T3 test is an important part of the thyroid function laboratory tests. Variations from Normal....

Ultrasonography of the Abdomen

Ultrasonography of the abdomen includes studies of organs and body tissues that are located in the abdominal cavity. These studies include abdominal aorta ultrasonography, an ultrasound study of the abdominal aorta gallbladder ultrasonography, an ultrasound study of the gallbladder and bile ducts kidney ultrasonography, an ultrasound study of the kidney structure and function liver ultrasonography, an ultrasound study of the liver and hepatic ducts pancreas ultrasonography, an ultrasound study...

Herpes Simplex

Herpes simplex is a viral infection characterized by localized primary lesions, latency, and recurrence in the localized areas. There are two types of herpes simplex virus herpes simplex type 1 (HSV-1) and herpes simplex virus type 2 (HSV-2). HSV-1 is the causative agent for fever blisters and cold sores, as well as more serious diseases such as meningoencephalitis. HSV-2 is the causative agent for herpes genitalis, a sexually transmitted disease of the urogenital tract. Primary and recurrent...

Human Chorionic Gonadotropin HCG

Human chorionic gonadotropin (HCG) is a hormone that appears in the blood and urine of pregnant women as early as ten days after conception. HCG is one of several hormones produced by the placenta. Blood-level measurement of this hormone has long been used to confirm pregnancy. The presence of HCG does not necessarily indicate a normal pregnancy. HCG levels can be used to diagnose a variety of reproductive-related pathologies. Levels vary throughout remainder of pregnancy Variations from...

Overview of Nuclear Scanning Studies

Diagnostic nuclear medicine involves the use of radionuclides, radioactive isotopes that undergo decay and are administered to the patient either orally or intravenously. Radionuclides are also known as tracers. As the radionuclide decays, it emits radiation that can be detected by specialized equipment. The radiation detection equipment is able to locate the concentration of radionuclides, known as uptake, in the tissues of the organ being studied. The equipment is able to convert the...

Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) is a noninvasive procedure that uses a magnetic field and radio waves to measure the activity of the body's hydrogen atoms. This activity is interpreted by computer and the information is converted into high-quality images that provide valuable diagnostic information. Magnetic resonance imaging is able to produce excellent detailed images of body organs and blood flow. MRI provides better contrast between normal and pathological tissue is able to produce images...

Venous Doppler Studies

Venous Doppler studies are ultrasound studies of the veins. These studies include examination of the veins of the lower extremities, the femoral, popliteal, and tibial veins veins of the upper extremities, the axillary and brachial veins and the jugular veins located in the neck. Venous Doppler studies are used to evaluate the flow of blood through the veins and to assess veins that are to be used in grafts. The patient is prepared for the exam by being placed in a supine position with the area...

Hotter Monitor Test

Holter monitoring, also called Holter electrocardiography, is a method of continuously recording the electrical activity of the heart over an extended period of time. Recordings are maintained on magnetic tape. The Holter monitor test is used to correlate suspected cardiac rhythm disorders with symptoms such as chest pain, syncope, and palpitations that may occur during the patient's daily activities. Holter monitoring is also used to evaluate pacemaker and defibrillation device efficiency, and...

Echocardiography

Echocardiography is an ultrasound examination that is performed to assess the structure and function of the heart. This study is sometimes called cardiac echo. Visualization of the heart chambers and valves can be accomplished with echocardiography. The shape, size, position, function, and blood flow through the heart can also be evaluated. In addition to providing information for diagnostic purposes, the procedure is performed to assess the condition of prosthetic heart valves. There are...

Genitalia and Anal Cultures

Cultures taken from the genitalia and anal canal in both men and women are often used to identify sexually transmitted diseases. Indications for these cultures are genital ulcers, signs and symptoms of sexually transmit ted diseases, pelvic inflammatory disease, or abnormal discharge and itching. Toxic shock syndrome and infections associated with the herpes simplex virus can also indicate a need for genital and anal cultures. Specific culture sites include the cervix, vagina, anal canal, and...

Cytomegalovirus CMV Antibody Test

Cytomegalovirus is a human viral pathogen that belongs to the herpes virus family. This virus causes serious illness in people with AIDS, in newborns, and in individuals being treated with immunosuppression therapy. CMV is the most common cause of posttransplant infection. The most severe form of CMV infection is seen in congenital infections. Infected newborns can exhibit permanent damage such as microcephaly, hydrocephaly, and chronic liver disease. Newborn diagnosis of CMV infection can be...

Cholesterol

One of the most tested lipids in the body, cholesterol is sometimes only associated with arteriosclerotic vascular disease. Cholesterol, however, is an important component of the body and is necessary for the production of bile acids, steroids, and cellular membranes. In addition, cholesterol plays a role in maintaining the skin's resistance to water-soluble substances and prevents excess evaporation of water from the body. About 75 of cholesterol is transported in the bloodstream via...

Electrocardiography Ecg Ekg

Electrocardiography is a recording of the electrical impulses that stimulate the heart to contract. It is one of the most frequently performed diagnostic tests. ECG is often ordered as part of a routine physical examination, in preparation for any surgical or procedural intervention, or to identify suspected heart conduction problems. Electrocardiography is also performed to monitor cardiac pacemaker function, and to evaluate the effectiveness of cardiac medications. The actual graphic report...

Nose and Throat Cultures

Cultures of the nose and throat are taken to search for specific disease-causing organisms, to diagnose bacterial infections, and to screen for carriers of Staphylococcus aureus or Haemophilus influenzae. Identification of the pathogenic organisms in the nose and throat can lead to definitive diagnoses such as thrush, diphtheria, pertussis, gonorrhea, and various viral upper respiratory infections. Specific culture sites include the nose, nasopharynx, and throat. Culture samples are taken by...

Testosterone

Testosterone, a male hormone, is responsible for sperm production and development of male secondary sex characteristics. Small amounts of testosterone are secreted by the ovaries and adrenal glands in women. Testosterone measurements assist in the assessment of various testicular conditions, pituitary function, and ovarian tumors or virilism in women. Variations from Normal. Increased testosterone levels in males can be caused by adrenal hyperplasia and adrenocortical or testicular tumors....

Prostate Specific Antigen PSA

Prostate specific antigen (PSA) is a protein found in normal prostate cells of all males. Identifying variations in the serum levels of this antigen is the most effective way to diagnose prostate cancer, identify tumor recurrence, and monitor the response to therapy for prostate carcinoma. The prostate-specific antigen and the prostatic acid phosphatase tests are used to identify and monitor tumors of the prostate. Variations from Normal. Caution must be used when interpreting PSA results....

Additional Abbreviations

ABO human blood grouping system anti-HBc antibody to hepatitis B core antigen anti-HBe antibody to hepatitis B envelope anti-HBs antibody to hepatitis B surface anti-HCV antibody to hepatitis C virus anti-VCA antibody to the viral capsid antigen EBNA antibodies to Epstein-Barr virus ECM, EM erythema chronicum migrans HBeAg hepatitis B envelope antigen HBsAg hepatitis B surface antigen HIV-1 human immunodeficiency virus VDRL venereal disease research laboratory

Urine Tests

Urine tests involve the analysis of the physical, chemical, and microscopic properties of urine. The physical analysis of urine includes examination of the odor, color, clarity, and specific gravity. Chemical analysis includes the assessment of bilirubin, blood (whole blood and hemoglobin), glucose, ketones, leukocyte esterase, nitrites, pH, protein, and urobilinogen levels. Microscopic analysis of the urine includes an examination of urine sediment for the presence of cells, crystals, casts,...

Overview of Doppler Ultrasound Studies

Doppler ultrasonography uses a transducer to detect Doppler shift waves, the sound frequency shifts created by moving blood cells. Audible sounds and waveforms are produced by the Doppler ultrasound detector as it recognizes the flow of blood through the blood vessel. These sounds are pulsations or swishing noises and are useful in determining the degree of blood vessel patency. The sounds and waveforms can be recorded on a videotape. Various Doppler techniques are available, depending on the...

Overview of Fecal Studies

Feces or stool is the waste product of digestion and is excreted by the gastrointestinal tract. Fecal studies are useful for identifying gastrointestinal conditions and disorders such as colorectal cancer, gastrointestinal bleeding, obstruction, inflammatory bowel disease, malabsorption, parasitic disease, pancreatitis, and bacterial infections. Normal feces consists of water, indigestible residue, intestinal secretions, large numbers of bacteria, bile, epithelial cells, white blood cells,...

Complement Fixation CF Test

The complement fixation (CF) test is used primarily to identify viral antibodies, but can be used to detect some fungal antibodies as well. Complement fixation is a complex test that relies on the ability of complement, an enzymatic serum protein, to interact with antibody and specific antigen to cause cell lysis. A negative result indicates an absence of the antibody being tested for, as evidenced by cell lysis. A positive result indicates that the antibody being tested for is present, as...

Endoscopic Studies of the Pelvic Cavity

Endoscopic studies of the pelvic cavity include studies that examine tissue and organs located in the pelvic region of the body. The examinations can be divided into two categories those related to the urinary tract, and those related to the reproductive system. Cystoscopy, an examination of the urethra, urinary bladder, and ureteral orifices and urodynamic studies, which measure the function of the urinary bladder, are included in the discussion of urinary tract endoscopies. Pelviscopy, an...

Insulin

Insulin, a hormone secreted by pancreatic beta cells, regulates metabolism of carbohydrates and is responsible for maintaining a constant blood glucose level. Insulin lowers blood glucose levels by promoting the transport of glucose from the bloodstream into the cells. Insulin levels can be measured by radioimmunoassay, a technique that uses radioactive substances to determine the concentration of specific blood constituents. Insulin levels are reported as microunits per milliliter ( xU mL)....

Calcitonin

Calcitonin, the hormone secreted by the parafollicular cells of the thyroid gland, functions to lower blood calcium levels. As serum calcium levels increase, calcitonin secretion also increases and the hormone encourages the movement of calcium from blood to the bones. Calcitonin also inhibits calcium reabsorption by the kidneys. The serum calcitonin test is used to evaluate individuals with suspected medullary carcinoma of the thyroid gland. Variations from Normal. Increased calcitonin levels...

Gastric Emptying Scan

The gastric emptying scan is a radionuclide study of the ability of the stomach to empty solids and fluids. This study is useful in diagnosing gastric motility abnormalities that interfere with the ability of the stomach to empty its contents in a timely manner. The patient is scanned after eating a special test meal that includes the radionuclides used for the scan. Once the meal has been ingested, the abdomen is scanned in both the sitting and supine positions. Gastric emptying time is...

Pancreas Ultrasonography

Pancreas ultrasonography is an ultrasound examination of the pancreas that is performed to assess the size, shape, texture, and position of the pancreas. Pancreatic malignancies and anomalies can be diagnosed with this ultrasound study. As with other needle aspiration biopsies, pancreatic ultrasound can be used to monitor needle insertion. With the patient in the supine position, the abdominal quadrants are exposed, conductive gel is applied to the epigastric area, and the transducer is moved...

Rh Typing

The presence or absence of the Rh antigen on the red blood cell membrane identifies human blood as Rh negative or Rh positive. Next to the A and B antigen blood grouping, the Rh antigen is the most important antigen in transfusion practice. There are many antigens in the Rh system, but the D antigen is the major one. Red blood cells that possess the D antigen are classified as Rh positive and cells that lack the D antigen are classified as Rh negative. Infectious Disease and Immunodiagnostic...

Spleen Scan

The spleen scan is a radionuclide study of the size, shape, and function of the spleen. Spleen scans identify abnormalities, tumors, obstructions, and cancer. Spleen trauma, rupture, and the impact on the spleen of lymphoma and leukemia can be assessed via nuclear medicine scans of the spleen. The procedure for the spleen scan is the same as that described under liver scan. Both static and flow images are produced, and SPECT imaging of the spleen may also be performed. Although considered safe,...

Thyroid Scans

There are several nuclear medicine thyroid studies, four of which are presented in this chapter. These scans are the general thyroid scan, iodine-131 scan, radioactive iodine uptake (RAIU) test, and thyroid stimulating hormone (TSH) study. Each scan is presented individually, although all have the same basic goal to assess the function and health of the thyroid gland. A thyroid scan is a radionuclide study of the thyroid gland. It is used to evaluate the size, position, shape, and function of...

Proctoscopy Sigmoidoscopy Proctosigmoidoscopy

Proctoscopy is an endoscopic examination of the anus and rectum with an instrument called a proctoscope, and sigmoidoscopy is an endoscopic examination of the sigmoid colon using a sigmoidoscope. When the anus, rectum, and sigmoid colon are examined at the same time, the procedure is known as a proctosigmoidoscopy and the instrument is called a proctosig-moidoscope. The endoscopes, which are inserted through the anal sphincter, can be rigid or flexible. The flexible fiberoptic instruments are...

Thyroid Function Tests

Anterior lobe of the pituitary gland. TSH stimulates the thyroid to produce and secrete the thyroid hormones thyroxine, triiodothyronine, and calcitonin. Assessment of thyroid function can be accomplished by measuring serum thyroid hormone levels and TSH levels. Clinical implications of increases or decreases of these substances are discussed individually. Thyroxine (T4) is the most abundant thyroid hormone secreted by thyroid follicular cells. Thyroxine increases the body's metabolic rate,...

Heart Function Tests

Special heart function tests covered in this chapter can be categorized as electrodiagnostic studies, which are procedures that use electrical impulses and electronic devices to identify and assess abnormalities of heart function and structure. The tests presented in this chapter are often performed to support or confirm information obtained with other diagnostic interventions. Heart function studies are covered individually and include electrocardiography (ECG, EKG), a study that measures the...

Fecal Tests

Fecal tests involve the analysis of the physical, chemical, microscopic, and microbiologic properties of feces. Physical examination of feces includes an analysis of the amount, color, consistency, odor, and shape. Chemical testing of feces includes chemical analysis to identify occult blood, carbohydrates, fats, bile, and trypsin. Microscopic testing of feces includes a microscopic examination to determine the presence of leukocytes, fats, and parasites. Microbiologic testing is presented in...

High Density Lipoprotein HDL

High-density lipoproteins (HDL) are plasma proteins that function as carriers of plasma cholesterol. Measuring the cholesterol contained in the HDL molecule is predictive of the individual's risk for coronary artery disease. It is believed that the HDL molecule carries cholesterol from the peripheral tissues of the body to the liver, where the cholesterol is converted into bile acids and eventually excreted. Cholesterol that is part of the high-density lipoprotein molecule will not be deposited...

Triglyceride

Triglycerides, the main form of stored fat in humans, are an important source of energy. Triglycerides exists in the bloodstream and are transported throughout the body by VLDLs and LDLs. Excess plasma triglycerides are stored in the body's adipose tissue. Measurement of triglyceride levels is part of the lipid profile. The triglyceride test is used to evaluate the individual's risk of coronary and vascular disease, and to identify atherosclerosis. The test can also provide information about...

Physical Examination of Feces

Physical examination of feces includes an analysis of the amount, color, consistency, odor, and shape of stool. In addition, some parasites may be identified. Physical observation of feces is not a routine laboratory test but is usually accomplished by a nurse in the hospital or home health setting. The patient may also be asked to describe the physical characteristics of his or her feces. Observations of changes in physical characteristics of feces may identify the need for further diagnostic...

Acid Phosphatase Prostatic Acid Phosphatase PAP

The enzyme acid phosphatase is present in various tissues, including bone, liver, kidneys, spleen, and red blood cells. Since the highest concentration of acid phosphatase, also known as prostatic acid phosphatase (PAP), is in the prostate gland, the diagnostic significance of acid phosphatase levels relates to that gland. Acid phosphatase levels are used to diagnose and stage cancer of the prostate, especially when the disease has metastasized to the bone. Acid phosphatase levels are used to...

Obstruction Series

The obstruction series, also known as an acute abdomen series, is a radiographic examination of the abdomen, bowel, and kidneys. The series con sists of at least two x-ray studies. The first film is an erect abdominal film that provides visualization of the diaphragms in order to detect air-fluid levels within the intestine. This film can also be accomplished as a left lateral decubitus film. The second film is very similar to the KUB, which has been previously discussed. Suspected bowel...

Chlamydia Antibody Tests

Chlamydia is a bacterium that requires living cells for growth. There are three recognized species of chlamydia, all of which are pathogenic to humans. Chlamydia infections are considered to be the most frequently occurring sexually transmitted disease in North America, particularly the United States. These infections occur primarily in the genitalia, and are also found in the conjunctiva, pharynx, urethra, and rectum. Chlamydia trachomatis is the species of chlamydia that causes trachoma,...

Overview of Urine Studies

The formation and excretion of urine by the kidneys is an essential body function. The kidneys excrete about 1500 milliliters of urine per day. Urine is about 95 water and 5 other constituents such as urea, electrolytes, amino acids, uric acid, creatinine, carbohydrates, bile pigments, and peptides. All substances found in the urine are also contained in the blood, but at different concentrations. The purpose of urine studies is to identify variations in substances normally found in the urine...

Composition of Blood

The average adult has about 5 liters (5-6 quarts) of blood, which is divided into plasma and cells. Plasma, which accounts for about 3 liters, is the liquid portion of blood. The cells, which account for about 2 liters, are referred to as the formed elements or cellular component of blood. Blood cells are classified as erythrocytes (red blood cells), leukocytes (white blood cells), and thrombocytes, also called platelets. Each type of blood cell has specific functions. A brief description of...

Lung Scans

Lung scans are radionuclide studies of the pulmonary system that are performed to assess pulmonary perfusion and pulmonary ventilation. Pulmonary perfusion is related to the blood flow throughout the lungs, and pulmonary ventilation refers to the patency of pulmonary airways. Ventilation also encompasses the air exchange between alveolar spaces and the atmosphere. The pulmonary perfusion scan, which requires the use of an intravenous radionuclide, is used to identify areas of the lung where the...

Wound Culture

Wound cultures are defined as laboratory tests that attempt to cultivate microorganisms that may be present in an infected wound. Wound infections are often visible even to the untrained eye. The presence of purulent and or foul-smelling drainage or other exudate is highly suggestive of wound infection and highly indicative for wound culture. Infection in nondraining wounds is evidenced by pain, swelling, and the presence of an abscess. Individuals with surgical wounds, burns, abrasions,...

Overview of Culture and Sensitivity C S Tests

Culture is defined as a laboratory test by which samples from body specimens are cultivated in a special growth medium in order to isolate the microorganisms that may be present. Culture is a highly effective laboratory method for identifying the microorganisms that cause infectious disease and for obtaining a definitive diagnosis. For example, a suspected diagnosis of strep throat is confirmed by culturing material taken from the infected throat and observing the growth of a specific type of...

Endoscopic Retrograde Cholangiopancreatography ERCP

Endoscopic retrograde cholangiopancreatography (ERCP) provides visualization of the biliary and pancreatic ducts. This study combines endoscopic and radiographic technology, and involves the use of a contrast medium. A side-viewing flexible endoscope is passed through the esophagus, the stomach, and into the duodenum. Using the endoscope, a small catheter is inserted into the ampulla of Vater, the site where bile and pancreatic juices flow into the small intestine. Radiographic dye or contrast...

Plasma Coagulation Factor Tests

As stated previously, coagulation factors are plasma proteins, with the exception of Factor IV calcium. These plasma proteins circulate in the blood in an inactive form and are activated when tissue or blood vessel damage occurs. Refer to Table 4-1 to review the name and number of each of the coagulation factors. In order for the coagulation process to be effective, there must not only be an adequate supply of each of the plasma coagulation factors but each factor must also be functional....

Interfering Circumstances

Pregnancy, recent isotope scans, and physical and emotional stress can cause increased Cortisol levels. Caffeine and smoking cause elevated Cortisol levels. Estrogen, oral contraceptives, and aldactone may also elevate Cortisol levels. Decreased levels are associated with drugs such as prednisone, androgens, and phenytoin. Gastrin is a hormone produced and secreted by specialized cells in the stomach. During normal gastric activity, gastrin stimulates the secretion of gastric acid, which aids...

Growth Hormone GH Somatotropin Somatotropic Hormone STH

Growth hormone (GH), also known as somatotropin and somatotropic hormone (STH), is released by the anterior lobe of the pituitary gland and is essential to all parts of the body that are associated with growth. This hormone affects the growth rate of children and adolescents, increases tissue mass, and stimulates cell division. Somatotropin is essential for the maintenance of the epiphyseal disk, the area where bone growth occurs, of long bones. Throughout life, growth hormone also plays a role...

Blood Glucose and Related Blood Sugar Tests

Glucose, a simple sugar, is the main blood carbohydrate and a major source of energy for all cells. The fasting blood sugar (FBS), postprandial blood sugar (PPBS), and the glucose tolerance test (GTT), or standard oral glucose tolerance test (SOGTT), are three of the most frequently performed blood sugar tests and are used to determine the level of glucose in the blood. Variations in blood glucose levels are broadly categorized as hyperglycemia, or increased blood sugar levels, and...

Glucose Tolerance Test GTT Standard Oral Glucose Tolerance Test SOGTT

The glucose tolerance test is a timed test of the glucose concentration in both the blood and urine. This test is used to confirm or rule out diabetes and is a definitive test for diagnosing hypoglycemia. After fasting overnight, the client is given a concentrated amount of glucose dissolved in a flavored, water-based drink. Blood and urine samples are collected over a three- to four-hour period. In health, the insulin response is immediate and in sufficient quantity to tolerate the glucose...

Electroencephalography EEG

Electroencephalography (EEG) is a diagnostic test that measures and records the electrical activity of the cerebral cortex. EEG is performed to diagnose diseases and disorders of the brain, to monitor cerebral blood flow during surgical procedures such as carotid endarterectomy, and to determine brain death. There are no contraindications for this test. Electroencephalography is usually performed in a room that is protected from outside interference. It can, however, be done at the patient's...

Cerebrospinal Fluid CSF Tests

Suppurative Meningitis

Cerebrospinal fluid (CSF) is a secretion of the choroid plexus, specialized tangled masses of capillaries located in the lateral, third, and fourth ventricles of the brain. CSF is a clear, colorless fluid that flows through the ventricles of the brain, the subarachnoid space, and the spaces associated with the spinal cord. Cerebrospinal fluid is often defined as the fluid shock absorber for the brain and spinal cord. In addition to cushioning these structures from shock, CSF helps transport...

Uric Acid

Uric acid is a product that is formed by the breakdown of nucleic acids. Most uric acid is excreted by the kidneys and some is excreted by the gastrointestinal tract. The main purpose of the uric acid test is to diagnose gout, a condition in which uric acid settles in tissues and joints, particularly joints of the big toe. The uric acid test is also used to monitor the treatment of gout. Women 2.0-6.6 mg dl Children 2.5-5.5 mg dl Variations from Normal. Hyperuricemia, increased uric acid in the...

Blood Groups ABO Red Cell Groups

Human blood is grouped according to the presence or absence of specific antigens that are found on the surface of red blood cells. The ABO system is the major human blood group system that is used to type or group blood according to the antigens present on the red blood cell. Group A blood has A antigens, group B blood has B antigens, group AB blood has both antigens, and group O blood has neither antigen. In addition to the blood group antigens, blood group antibodies are present in human...

Colonoscopy

Colonoscopy is an endoscopic examination of the full length of the large intestine from the anus to the ileocecal valve. A flexible fiberoptic colono-scope, which is inserted via the anus, allows the physician to examine the mucosa of the entire colon and the terminal ileum. The patient is sedated with intravenous medication and, once the colonoscope is in place, air is injected to expand the bowel and allow for better visualization of the large intestine. Figure 12-3 is a sample colonoscopy...