blood test

 

examination of blood routinely or as an aid in diagnosing a suspected disease. Tests may be performed on whole blood or on the plasma portion only. Blood typing identifies the proteins at specific sites on red blood cells, a necessity in determining compatibility for blood transfusion. Human Lymphocyte Antigens (HLA) is a form of white blood cell typing prerequisite for organ and bone marrow transplants. The Coulter Cell Counter is widely used in electronic counts of red blood cells for the diagnosis of anemia and polycythemia. White cell counts are vital in detecting infections or in confirming leukemia. Serum or plasma may be collected, cultured, and inoculated with bacteria or other substances for the purpose of detecting the body's reaction to infections, cancer, or HIV, the virus that causes AIDS. Plasma may also be examined for evidence of functional disorders, e.g., for blood sugar in testing for diabetes mellitus. Blood tests for tumor markers, such as prostate-specific antigen, are effective in detecting cancer in high risk groups. Almost all blood tests are now performed by electronic equipment, and results are evaluated and printed out by computer.

Bloodwork redirects here. For the 2002 film, see Blood Work. For the 36 Crazyfists Song, see Bloodwork (Song)

Blood tests are laboratory tests done on blood to gain an appreciation of disease states and the function of organs. Since blood flows throughout the body, acting as a medium for providing oxygen and other nutrients, and drawing waste products back to the excretory systems for disposal, the state of the bloodstream affects, or is affected by, many medical conditions. For these reasons, blood tests are the most commonly performed medical tests. Blood is obtained from one of the patient's veins by venipuncture or fingerprick, except for tests such as Arterial blood gas.

Blood is useful as it is a relatively non-invasive way to obtain cells, and extracellular fluid (plasma), from the body to check on its health. Although the term blood test is used, most routine tests (except for most haematology) are done on plasma or serum.

The list below includes both specific tests, and general techniques.

Blood chemistry tests

A basic metabolic panel measures sodium, potassium, chloride, bicarbonate, blood urea nitrogen (BUN), magnesium, creatinine, and glucose. It also sometimes includes calcium.

While the regular glucose test is taken at a certain point in time, the glucose tolerance test involves repeated testing to determine the rate at which glucose is processed by the body.

While the above tests are all taken from venous blood, by contrast the arterial blood gas test is, as its name would suggest, taken from arterial blood, and is therefore more dangerous and uncomfortable.

Large organic molecules

Proteins

• Protein electrophoresis (general technique -- not a specific test)
• Western blot (general technique -- not a specific test)
• Liver function tests

Antibody Proteins

• Serology (general technique -- not a specific test)
  • Wassermann test (for syphilis)
• ELISA test
• Coombs test

Other

• Polymerase chain reaction (DNA). DNA testing is today possible with even very small quantities of blood: this is commonly used in forensic science, but is now also part of the diagnostic process of many disorders.
• Northern blot (RNA)

Cells

• Full blood count (or "complete blood count")
• Hematocrit and MCV ("mean corpuscular volume")
• Erythrocyte sedimentation rate (ESR)
• Cross-matching. Determination of blood type for blood transfusion or transplants
• Blood cultures are commonly taken if infection is suspected. Positive cultures and resulting sensitivity results are often useful in guiding medical treatment.

External links

• Cold autoantibody webpage on "health a to z"

See also

• Reference ranges for common blood tests (with a much longer list)
• Urine test
• HIV test (uses several different techniques, including ELISA test and Western blot)
• Blood film
• Hematology
• Microbiology
• Medical technologist

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