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Blood Tests

Blood tests help doctors check for certain diseases and conditions. They also help check the function of your organs and show how well treatments are working.

PubMed Health Glossary
(Source: NIH - National Heart, Lung, and Blood Institute)

Blood Tests

Blood tests help doctors check for certain diseases and conditions. They also help check the function of your organs and show how well treatments are working.

Specifically, blood tests can help doctors:

Overview

Blood tests are very common. When you have routine checkups, your doctor may recommend blood tests to see how your body is working.

Many blood tests don't require any special preparations. For some, you may need to fast (not eat any food) for 8 to 12 hours before the test. Your doctor will let you know how to prepare for blood tests.

During a... Read more about Blood Tests

What works? Research summarized

Evidence reviews

Does employing general practitioners to provide care for patients with non‐urgent problems in emergency departments decrease resource use and costs?

An important portion of patients who attend hospital emergency departments (EDs) present with health problems that are classified as non‐urgent. With many EDs experiencing long‐waits and overcrowding, it has been suggested that providing primary care services in EDs for patients with non‐urgent problems may be an efficient and cost‐effective alternative to emergency care.

Blood clotting analysers (TEG or ROTEM) versus any comparison to guide the use of blood products in adults or children with bleeding

The ability to make a sufficient blood clot is crucial in participants with bleeding. Clotting can be measured by various tests. TEG and ROTEM tests have the advantage of showing the total clotting capacity. These tests are performed at the bedside, and generally provide a rapid and useful result, guiding clinicians towards a more goal‐directed transfusion management.

Screening for colorectal cancer using the faecal occult blood test, Hemoccult

Regular screening of faeces for blood can detect colorectal cancer earlier and hence may reduce mortality in populations at risk, such as older patients. The screening test used in these trials to detect colorectal (bowel) cancer was the faecal occult blood test (FOBT). If the FOBT is positive, the bowels are examined closely with further diagnostic test (coloscopy, flexible sigmoidoscopy, double‐contrast barium enema), but these tests often cause discomfort and can cause serious adverse consequences. As blood identified in faeces may be due to several reason (unrelated to cancer), it may cause people unnecessary stress and expose them to possible harm. This review found that FOBT screening is likely to avoid approximately 1 in 6 colorectal cancer deaths.

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Summaries for consumers

Does employing general practitioners to provide care for patients with non‐urgent problems in emergency departments decrease resource use and costs?

An important portion of patients who attend hospital emergency departments (EDs) present with health problems that are classified as non‐urgent. With many EDs experiencing long‐waits and overcrowding, it has been suggested that providing primary care services in EDs for patients with non‐urgent problems may be an efficient and cost‐effective alternative to emergency care.

What kinds of allergy tests are there?

Various tests can be used to find out what kind of substance is causing an allergic reaction: skin tests, blood tests and challenge tests. Your doctor will usually decide which test to use based on your description of the symptoms and your medical history.

Blood clotting analysers (TEG or ROTEM) versus any comparison to guide the use of blood products in adults or children with bleeding

The ability to make a sufficient blood clot is crucial in participants with bleeding. Clotting can be measured by various tests. TEG and ROTEM tests have the advantage of showing the total clotting capacity. These tests are performed at the bedside, and generally provide a rapid and useful result, guiding clinicians towards a more goal‐directed transfusion management.

See all (356)

Terms to know

Blood
A tissue with red blood cells, white blood cells, platelets, and other substances suspended in fluid called plasma. Blood takes oxygen and nutrients to the tissues, and carries away wastes.
Blood Plasma
The clear, yellowish, fluid part of the blood that carries the blood cells. The proteins that form blood clots are in plasma.
Bone Marrow
The soft, sponge-like tissue in the center of most bones. It produces white blood cells, red blood cells, and platelets.
Enzymes
Protein made by the body that brings about a chemical reaction - for example, the enzymes produced by the gut to aid digestion.
Erythrocytes (Red Blood Cells)
A cell that carries oxygen to all parts of the body.
Hematocrit
A measure that tells what portion of a blood sample consists of red blood cells. Low hematocrit suggests anemia or massive blood loss.
Hemoglobin
A protein inside red blood cells that carries oxygen from the lungs to tissues and organs in the body and carries carbon dioxide back to the lungs.
Leukocytes (White Blood Cells)
A type of immune cell. Most white blood cells are made in the bone marrow and are found in the blood and lymph tissue. White blood cells help the body fight infections and other diseases. Granulocytes, monocytes, and lymphocytes are white blood cells.
Platelets (Thrombocytes)
A tiny piece of cell that is made by breaking off of a large cell in the bone marrow. Platelets are found in the blood and spleen. They help form blood clots to slow or stop bleeding, and to help wounds heal. Also called thrombocyte.
Triglycerides
One of the major forms of fat that is produced in the liver and found in the blood.

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Other terms to know: See all 10
Blood, Blood Plasma, Bone Marrow

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