Glossary of Terms - c

Index

Click on a letter to jump to another subsection or click on "all" for the entire document.

a b c d e f g h i k l m n o p q r s t u v w all

Terms

C-reactive protein (CRP): A protein that appears, usually within 24 hours, in the blood during the acute stage of inflammatory disorders such as rheumatic fever, or after a myocardial infarction (heart attack). The serum level of CRP is a sensitive indicator and monitor of rheumatic activity.
Calcium (Ca): An alkaline element found in most tissues, it is an abundant mineral in the body. It is essential for maintenance of bones and teeth, normal heart, muscle, and nerve functions, as well as normal blood clotting. Calcium levels can be measured in the blood or urine to help detect thyroid and parathyroid disorders, bone diseases, and certain cancers. It may also point to the presence of kidney stones.
Cannabinoids: The psychoactive chemical substances found in marijuana (Cannabis sativa). The presence of cannabinoids in urine or blood indicates recent marijuana use or close contact with it.
Carbamazepine: A pain relieving and anticonvulsant drug often used to treat trigeminal neuralgia (pain along the route of the facial nerve) and epilepsy (a neurological disorder characterized by convulsive seizures). Blood testing can determine carbamazepine levels in the body and aid in maintaining appropriate dosage.
Carbohydrate: A group of organic compounds, including starches and sugars, that is a major source of body energy and is necessary for metabolism. Excessive intake is associated with tooth decay and obesity. Its concentration can be assayed in serum and urine.
CAT scan (computer or computerized axial tomography): See computed tomography.
Catalyze: To accelerate the rate of a chemical reaction by a substance that is not permanently affected in the process.
Chemiluminescent: Exhibiting light as a result of a chemical reaction without the production of heat; emitted from some bacteria, fungi, and fireflies.
Chemistry: In clinical testing, refers to the solutes dissolved in the plasma such as uric acid, etc.
Chlamydia trachomatis: The causative microorganism of one of the most prevalent sexually transmitted diseases, Chlamydia infection can lead to urethritis (inflammation of the urethra), pelvic inflammatory disease, ectopic pregnancy, and infertility. The infection may be asymptomatic, but patients may experience vaginal irritation or burning, discharge from penis or vagina, or pain. This microorganism is also the cause of serious eye infections. At one time testing for Chlamydia was somewhat difficult; now, however, immunoassay can detect the antigens from swab specimens.
Chloride: A compound in which one of the elements is chlorine (sodium chloride — table salt — is the most common example); found in the body in large amounts. It is an electrolyte, thus is involved in water balance and acid-base balance. (Electrolytes affect movement of substances throughout the body and are crucial for normal function and metabolism.) To help determine electrolyte, fluid, kidney, and adrenal gland disorders, chloride levels usually are measured in blood, but also may be tested for in urine.
Cholesterol: A fat-soluble substance present in the blood and in animal fats that facilitates absorption and transport of fatty acids, and is necessary in hormone production. High levels of blood cholesterol have been linked to atherosclerosis and heart disease. See high and low density lipoprotein cholesterols.
Chorionic villi sampling: A means of testing the fetus for various abnormalities, such as congenital defects, blood disorders, and inborn errors of metabolism. This test can be performed during the first trimester of pregnancy, but is easier to carry out between the 14th and 16th weeks of pregnancy.
Chromosomes: The 46 (in human beings) structures in the nuclei of cells on which the genes, which contain hereditary information, are arranged.
Chronic carrier: Carrier: someone who has been infected by a pathogenic organism and has no symptoms of the illness, but has the ability to infect others.
Chronic hepatitis B: Long-term infection with the hepatitis B virus. (Hepatitis B also has been called serum hepatitis.) Such infection may lead to liver cell destruction and cirrhosis.
Cirrhosis: A degenerative disease of the liver ¿ the organ that helps eliminate toxic materials from the body ¿ often caused by alcoholism, but also may result from certain forms of hepatitis. Cirrhosis is characterized by formation of fibrous tissue, nodules, and scarring, which interfere with liver cell function and blood circulation. Symptoms include weakness, weight loss, fatigue, abdominal swelling due to fluid accumulation, and tenderness and enlargement of the liver. Tests for prolonged prothrombin time and decreased albumin are among those used to detect cirrhosis. See prothrombin and albumin.
Cocaine: A substance used as a local anesthetic, also used as a recreational inhalant, that can lead to psychological dependence with prolonged use. Its use can cause damage to mucous membranes and cardiovascular disorders. Cocaine metabolites can be detected in urine and may indicate recent use of the drug.
Colonoscopy: Visualization of the lining of the anus, rectum and colon through a rigid proctosigmoidoscope or a flexible fiber optic endoscope (types of viewing tubes). This procedure allows diagnosis of tumors and inflammatory diseases.
Colorectal cancer: A malignant disease of the colon and/or rectum which often begins as a polyp. The first indication of colorectal cancer is usually hidden, or occult, blood in the stool. Symptoms may include changes in bowel habits (diarrhea, constipation) or in consistency or color of the stool. A stool specimen blood test is commonly performed to screen for colorectal cancer.
Colorimetric: Pertaining to measurement of concentration of a solution based on its absorption or transmission of light, or on the intensity of color in a liquid.
Combination testing: A series of independent tests done on single specimens to arrive at a medical decision.
Competitive-binding assay: An analytic procedure in which an unlabeled and a labeled analyte compete for sites to bind to a specific protein.
Complement: A group of serum proteins that destroy sensitized cells or bacteria.
Complete blood count (CBC): The determination of the blood cells in a definite volume of blood that includes separate counts for red and white blood cells.
Computer tomography (CT): A radiographic scanning procedure to obtain cross-sectional images. The X-ray source rotates about the patient, generating X-rays which pass through the individual and are monitored as they exit, by detectors that are linked to a computer. The computer constructs three-dimensional images for examination and analysis. CT has revolutionized the diagnosis of intracranial, intrathoracic, and intraabdominal tumors, as well as other space-occupying lesions. CAT scan (computer axial tomography), CTAT (computerized transaxial tomography), CRT (computerized reconstruction tomography), and DAT (digital axial tomography) are diagnostic radiographic tools that are now collectively called computed tomography.
Conjugate: An analyte or antibody which has been tagged with an enzyme tracer.
Core window: The period during which a person infected by the hepatitis B virus may infect others, even though blood tests show neither hepatitis B surface antigen nor antibodies to hepatitis core antigen.
Creatine kinase (CK): An isoenzyme (an enzyme that appears in multiple forms) found in high concentrations in heart and skeletal muscles, and, in smaller amounts, in brain tissue. Each form of CK is predominant in specific tissues. Determining blood levels of the isoenzyme will aid in detection of myocardial infarction and muscle diseases such as muscular dystrophy.
Creatinine: Found in muscle and blood and excreted in urine, creatinine is the end product of muscle (creatine) metabolism. By ascertaining levels of creatinine in blood or urine or in both, presence or severity of kidney malfunction can be indicated.
Cross-reactivity: The ability of an antibody to react with or bind an antigen that did not stimulate its production.
Culture: A procedure in which material or microorganisms from varying sources are cultivated in (culture) media for diagnostic or treatment purposes. Cultures also are performed to detect whether viable microorganisms are present, and, therefore, an infection exists. Growth and identification of the organisms present allow suitable selection of treatment (antibiotics). The cultivation product or the material to be cultivated also may be referred to as a culture.