Blood test

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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, 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 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.

Contents

Chemistry

Specific biochemical blood tests include:

Electrolytes
Blood urea nitrogen ("BUN") and renal function (creatinine is generally used)
Liver enzymes
Glucose and oral glucose tolerance test (which involves a series of blood tests)
Protein electrophoresis
Chem7 test - a battery of blood chemistry tests; the seven parts of a Chem7; sodium, potassium, chloride, bicarbonate, blood urea nitrogen (BUN), creatinine, and glucose

Hematology

Hematological tests are:

Full blood count (or "complete blood count")
Haematocrit and MCV ("mean corpuscular volume")
Erythrocyte sedimentation rate (ESR)
Determination of blood type for blood transfusion.

Techniques

General biochemical techniques often used in blood testing include:

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.

Serology

Serology are blood tests are often used to diagnose sexually transmitted diseases. Some jurisdictions insist on blood tests before marriage. Many states also require blood tests for all newborn babies.

HIV test
Wassermann test (for syphilis)