- Did you know?
The term “blood group” refers to the entire blood group system comprising red blood cell (RBC) antigens whose specificity is controlled by a series of genes which can be allelic or linked very closely on the same chromosome. “Blood type” refers to a specific pattern of reaction to testing antisera within a given system. Over a period of time, our understanding on blood groups has evolved to encompass not only transfusion-related problems but also specific disease association with RBC surface antigens. Karl Landsteiner has been credited for the discovery of ABO blood group system in 1900. His extensive research on serology based on simple but strong scientific reasoning led to identification of major blood groups such as O, A, and B types, compatibility testing, and subsequent transfusion practices.
At present, 33 blood group systems representing over 300 antigens are listed by the International Society of Blood Transfusion. Most of them have been cloned and sequenced. The genes of these blood group systems are autosomal, except XG and XK which are X-borne, and MIC2 which is present on both X and Y chromosomes. The antigens can be integral proteins where polymorphisms lie in the variation of amino acid sequence (e.g., rhesus [Rh], Kell), glycoproteins or glycolipids (e.g., ABO).
Among the 33 systems, ABO remains the most important in transfusion and transplantation since any person above the age of 6 months possess clinically significant anti-A and/or anti-B antibodies in their serum. Blood group A contains antibody against blood group B in serum and vice-versa, while blood group O contains no A/B antigen but both their antibodies in serum.
Benefits of donating blood:
According to the American Journal of Epidemiology,” it was found that blood donors are 88% less likely to suffer a heart attack than those who do not donate” (Salonen et al). Furthermore, Gustaf. Edgren, believes that donating blood frequently is related to reducing the chance of getting some cancers, such as liver, lung, colon, stomach and throat cancers. Therefore, the advantages of donating blood far outweigh any disadvantage which may be perceived.
To lower the risk of heart disease is to donate blood. “Because high body iron stores have been suggested as a risk factor for acute myocardial infarction, donation of blood could theoretically reduce the risk by lowering body iron stores.”(Salonen et al.) According to this study, 88% of people who donate repeatedly do not suffer from heart attacks rather than people who do not donate. Therefore, donating blood helps to lower this risk and keep the heart healthy.
One of many advantages of donating blood is that blood donation can reduce the risk of cancer. Donating blood will decrease the excessive amount of stored iron, which is considered to be a high risk of cancer.
Additionally, Dr. Gregory Sloop, claims that blood donation may reduce viscosity of blood which has been associated with increased risk of cardiovascular disease. It is recommended that people should donate blood at least once a year as it has many advantages for health.
Blood transfusions and Thalassemia:
Thalassemia is a genetic blood disorder. People with Thalassemia disease are not able to make enough hemoglobin, which causes severe anemia. Hemoglobin is found in red blood cells and carries oxygen to all parts of the body. When there is not enough hemoglobin in the red blood cells, oxygen cannot get to all parts of the body. Organs then become starved for oxygen and are unable to function properly.
Blood transfusion is the mainstay of care for individuals with thalassemia major and many with intermedia. The purpose of transfusion is twofold: to improve the anemia and to suppress the ineffective erythropoiesis. Chronic transfusions prevent most of the serious growth, skeletal, and neurological complications of thalassemia major. However, once started, the transfusion-related complications become a major source of morbidity. Standards must be developed and maintained to ensure a safe and rational approach to the use of blood transfusions in the management of these rare disorders.
Patients with ß+/ß+ thalassemia; hemoglobin E-ß thalassemia; hemoglobin H disease; and hemoglobin H–Constant Spring often have a thalassemia intermedia phenotype and do not necessarily require chronic transfusion. However, the DNA mutations do not reliably predict the clinical phenotype. ß0/ß+ and even ß0/ß0 may occasionally have a thalassemia intermedia clinical phenotype. The clinical phenotype of thalassemia intermedia patients may change as they age and may require transfusion therapy. Ongoing assessment of transfusion requirements is necessary for both thalassemia major and intermedia.
The decision to start transfusions is based on inability to compensate for the low hemoglobin (signs of increased cardiac effort, tachycardia, sweating, poor feeding, and poor growth), or less commonly, on increasing symptoms of ineffective erythropoiesis (bone changes, massive splenomegaly). The decision to institute chronic transfusion should not be based exclusively on the presence of anemia.
The decision to initiate chronic transfusion therapy requires significant input from the patient, family, and medical team. Anemia alone is not an indication of the need for chronic transfusion. Anemia should be linked with a significant impairment in quality of life or associated morbidities. Factors to consider include: poor growth; inability to maintain daily routines and activities such as going to school and work; evidence of organ dysfunction; evidence of cardiac disease; pulmonary hypertension; and dysmorphic bone changes.
It may be necessary to initiate a six-month trial of blood transfusions in patients of families whose decision to transfuse is uncertain. After six months, transfusions can be stopped and the patient observed for a brief period of time to give the family and medical team information as to the clinical benefits and psychological impact of the transfusions.