Hemolytic Information and Courses from MediaLab, Inc.

In thalassemia there is often an excess production or accumulation of globin chains produced by genes that are not effected by the thalassemia deletion. In alpha thalassemia this may be seen as gamma chain tetramers (hemoglobin Bart's) in the unborn child and as beta chain tetramers (hemoglobin H) in adults. Tetramer accumulation often leads to red blood cell damage and hemolytic anemia.

Bilirubin is formed as a result of hemoglobin degradation. Normally, senescent red blood cells are removed from circulation and the bilirubin that is formed is processed by the liver. The normal level of bilirubin in the serum of adults is 0.2-1mg/dl. Bilirubin levels increase with liver disorders and also in anemia that is a result of a hemolytic process. Patients may display jaundice when serum bilirubin levels exceed 2mg/dl.Persons with alpha thalassemia intermedia usually have an increased bilirubin level, because of ongoing hemolysis. This bilirubin is typically the unconjugated fraction of bilirubin.

No blood is found in the urine of healthy individuals although samples from menstruating females, frequently, but not always, test positive for blood. Hematuria is associated with renal or genital urinary disorders in which the bleeding is the result of irritation to the involved organs or trauma. Examples include renal calculi, pyelonephritis, glomerulonephritis, tumors, trauma or exposure to toxic chemicals or drugs and/or strenuous exercise. Hemoglobinuria may be due to the lysis of red cells within the urinary tract. If it is caused by intravascular hemolysis, the hemoglobin is then filtered through the glomeruli. In the normal individual, the hemoglobin molecule attaches to haptoglobin and in this way bypasses the kidney filtration system. When the hemoglobin/haptoglobin system is overwhelmed, as in cases of hemolytic anemia, severe burns, transfusion reaction, infection or strenuous exercise, hemoglobin passes into the urine.

Urinary urobilinogen may be increased in the presence of a hemolytic process such as hemolytic anemia. It may also be increased with infectious hepatitis, or with cirrhosis. Comparing the urinary bilirubin result with the urobilinogen result may assist in distinguishing between red cell hemolysis, hepatic disease, and biliary obstruction. Urobilinogen is increased in hemolytic disease and urine bilirubin is negative. Urobilinogen is increased in hepatic disease, and urine bilirubin may be positive or negative. Urobilinogen is low with biliary obstruction, and urine bilirubin is positive. Reagent strips methods however, cannot distinguish normal urobilinogen from absent urobilinogen, as might be seen in complete biliary obstruction.

A screening test for bilirubin in the urine is included in most urine dipsticks and may be present when liver disease or damage is suspected. Bilirubinuria can be detected before other clinical symptoms such as jaundice are present or recognizable. The detection of small quantities is very important in early diagnosis of obstructive and hepatic jaundice. This test is also useful in the differential diagnosis of obstructive jaundice (positive for bilirubinuria) vs. hemolytic jaundice (negative for bilirubinuria).

The predominant immunoglobulin class for the B antibodies produced by individuals with group A phenotype and the A antibodies produced by individuals with group B phenotype is IgM. Small quantities of IgG may also be present. IgG is the predominant immunoglobulin for the anti-A and anti-B antibodies found in individuals with group O phenotype. Infants of group O mothers are at higher risk for hemolytic disease of the newborn (HDN) than those born to mothers with group A or B because IgG immunoglobulins readily cross the placenta. IgM molecules do not readily cross the placenta because of their larger size. It is important to note that immune antibodies are usually IgG. Both naturally occurring and immune ABO antibodies are critically important in transfusion since both sensitize and usually hemolyze red cells with the corresponding antigen.

Sentinel Events are sentinels--they function as guards or watchkeepers. They indicate serious situations that require immediate attention: Patient deathParalysisComaPermanent loss of functionAny procedure on the wrong patient, the wrong side of the body, or the wrong organ Hemolytic transfusion reaction involving major blood group incompatibility

Schistocyte is a general term for a fragmented red blood cell that may assume various shapes, some with horn-like projections (keratocytes), triangle-forms (triangulocytes), and helmet shapes, as illustrated in the upper photograph. Schistocytes are formed when erythrocytes are forced through a vessel blocked with interlacing fibrin strands and the red cells are sliced into fragments. True schistocytes are devoid of central pallor. These damaged cells continue to circulate while healing their torn edges. Finally, they are removed by the spleen. Bite cells (lower photograph) appear when an abnormal hemoglobin aggregate (Heinz body) is nibbled out of a red cell's cytoplasm by the spleen leaving a bitten apple appearance. Glucose 6-PD deficiency secondary to chemical poisoning or injury by oxidant drugs are settings for Heinz body formation, and the telltale bite cells remain as evidence. Hemolytic anemia associated with severe liver disease is another setting where bite cells are formed.

The photograph represents peripheral blood smear findings in another patient with hereditary spherocytosis. The red cells vary in size (anisocytosis)with a mixture of microcytes (red cells with central pallor) and microspherocytes (red cells with central staining). Macrocytes are conspicuous, some staining light blue. They are immature erythrocytes (reticulocytes)released from the bone marrow early. The bone marrow, geared up for rapid cell release in response to severe hemolysis, expels young red blood cells into the circulation before completing their 24 hour maturation cycle. Hemolysis, jaundice, and gall stone formation disappear following splenectomy. Gallbladder and stone removal eliminate the right upper quadrant pain. A serious consideration, especially in children with hereditary spherocytosis, is hemolytic crisis. A viral infection may allow red blood cell destruction to continue unabated. Anemia of such sudden onset and severity may become catastrophic, with death as the outcome. Splenectomy removes this possibility.

A microcyte with normal hemoglobin content (one-third of central pallor) can be seen in the center of this field, just below and to the left of the lymphocyte. Since many of the other cells in this field are normal or larger than normal, the MCV would be within the normal range although the diameter and volume of this individual cell would be lower than normal. This type of microcyte can be seen in some hemolytic anemias and the rare enzyme deficiency, pyruvate kinase deficiency anemia.

Another example of microcytes seen in a slide from a patient with hemolytic anemia. Compare the two microcytes in the center of the field with the lymphocyte to the right. Notice the larger red cell just below the microcytes is about the same size as the lymphocyte. Several other microcytes can also be seen in this field.

Examples of conditions in which spherocytes can be seen include hereditary spherocytosis and immune hemolytic anemias (i.e., ABO incompatibility). Spherocytes can also form in conditions where there has been a direct physical or chemical injury to the cells, such as heat. An example would be a smear from an individual who has suffered severe burns. In each of the above conditions, tiny bits of membrane are removed from the adult red cells, leaving the cell with a decreased surface/volume ratio. In hereditary spherocytosis where spherocytes are numerous, the MCHC value will be at the upper limits of normal, or about 36. The identification of spherocytes on the smear of a patient with hereditary spherocytosis can aid significantly in the diagnosis of the disorder. In vitro conditions which will cause spherocytes include prolonged storage, i.e. stored bank blood.