Dictionary:
he·mol·y·sis (hĭ-mŏl'ĭ-sĭs, hē'mə-lī'sĭs) ![]() |
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The breakdown of red blood cells and the release of hemoglobin that occurs normally at the end of the life span of a red blood cell.
| Columbia Encyclopedia: hemolysis |
| Veterinary Dictionary: hemolysis |
Rupture of erythrocytes with release of hemoglobin.
In a transfusion reaction or in alloimmune hemolytic anemia antibody mediated lysis of red blood cells involves triggering of the complement cascade. Red blood cells also clump together. The agglutinated cells become trapped in the smaller vessels or are phagocytosed and eventually disintegrate.
Some microbes form substances called hemolysins that have the specific action of destroying red blood cells; beta-hemolytic streptococci are an example.
Intravenous administration of a hypotonic solution or plain distilled water will cause the red cells to fill with fluid until their membranes rupture and the cells are destroyed.
Wherever either in vitro or in vivo IgG or IgM antibodies are bound to red blood cell antigens in the presence of complement, the complement cascade is triggered the final products of which include enzymes that result in holes being ‘punched’ in the wall of the red blood cell, allowing hemoglobin to escape and which is observed as lysis.
Snake venoms and certain plant substances may cause hemolysis. A great variety of chemical agents can lead to destruction of erythrocytes if there is exposure to a sufficiently high concentration of the substance. These chemical hemolytics include copper.
A disorder of the immune response in which antibodies are made to ‘self’ red blood cell antigens resulting in the lysis of the cells. See also autoimmune hemolytic anemia.
| Wikipedia: Hemolysis |
Haemolysis (or hemolysis)—from the Greek Hemo-, Greek Αἷμα meaning blood, -lysis, meaning to break open—is the breaking open of red blood cells and the release of hemoglobin into the surrounding fluid (plasma, in vivo).
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In vivo (inside the body) hemolysis, which can be caused by a large number of conditions, can lead to anemia.
Anemias caused by in vivo hemolysis are collectively called hemolytic anemias.
In vitro (outside the body) hemolysis can be an important unwanted effect in medical tests and can cause inaccurate results, because the contents of hemolysed red blood cells are included with the plasma. The concentration of potassium inside red blood cells is much higher than in the plasma and so an elevated potassium is usually found in biochemistry tests of hemolysed blood. If as little as 0.5% of the red blood cells are hemolysed the serum will have a visually obvious pinkish colour, due to hemoglobin.
Most causes of In vitro hemolysis are related to specimen collection. Difficult collections, unsecure line connections, contamination, and incorrect needle size, as well as improper tube mixing and incorrectly filled tubes are all frequent causes of hemolysis. Excessive suction can cause the red blood cells to be literally smashed on their way through the hypodermic needle owing to turbulence and physical forces. Such hemolysis is more likely to occur when a patient's veins are difficult to find or when they collapse when blood is removed by a syringe or a modern vacuum tube. Experience and proper technique are key for any phlebotomist or nurse to prevent hemolysis. In vitro hemolysis can also occur in a blood sample owing to prolonged storage or storage in incorrect conditions (ie too hot, too cold).
In some surgical procedures (especially some heart operations) where substantial blood loss is expected, machinery is used for intraoperative blood salvage. A centrifuge process takes blood from the patient, washes the red blood cells with normal saline, and returns them to the patient's blood circulation. Hemolysis may occur if the centrifuge rotates too quickly (generally greater than 500 rpm)—essentially this is hemolysis occurring outside of the body. Unfortunately, increased hemolysis occurs with massive amounts of sudden blood loss, because the process of returning a patient's cells must be done at a correspondingly higher speed to prevent hypotension, pH imbalance, and a number of other hemodynamic and blood level factors.
Hemolytic patterns of the various Gram positive cocci; Streptococci are differentiated by hemolysis of red blood cells on blood agar (BA) plates.
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| hemolysate | |
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| isohemolysin |
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