Chapter 11 The Blood 341 Copyright Goodheart-Willcox Co., Inc. Sickle Cell Anemia Recall that normal RBCs are disc-shaped. However, the RBCs of a person with sickle cell anemia are shaped like a crescent or sickle, a large cutting instrument with a curved metal blade (Figure 11.17). The hemoglobin molecules in the RBCs of a patient with sickle cell anemia are misshaped, causing the RBCs to take on the abnormal shape. Sickle-shaped hemoglobin molecules carry less oxygen than normal hemoglobin molecules. Because of their shape and sticky texture, sickle-shaped RBCs easily become stuck in small blood vessels, disrupting normal blood flow. Figure 11.17 illustrates how the sickle-shaped RBCs become lodged in blood vessels. Symptoms of sickle cell anemia include excruci- atingly painful episodes called crises. Crises can last anywhere from a few hours to several days, and these episodes require hospitalization. The pain associated with crises usually occurs in the back and around long bones, such as the femur, where tissues can be damaged from oxygen deprivation. Other symptoms include bacterial infection, fatigue, shortness of breath, rapid heart rate, and jaundice, a yellowing of the skin and eyes. Strokes may also occur if RBCs become lodged in the small vessels of the brain. Treatment of sickle cell anemia may require daily doses of antibiotics to prevent bacterial infection, especially in small children who have the disease. Blood transfusions are given frequently to increase RBC count. Folic acid supplements are also recom- mended. In the event of a crisis, patients are given blood transfusions, pain medications, and fluids. Individuals who inherit the sickle cell gene from only one parent have the sickle cell trait, which means they are a carrier but will not develop any of the symptoms of the disease. Sickle cell anemia is most common in African-Americans and individuals of Mediterranean descent. In the past, sickle cell anemia resulted in death at an early age, but medical advances are helping people with this disease live to 50 years of age and beyond. Thalassemia Thalassemia, also called Cooley’s anemia, is a type of anemia that affects hemoglobin. This condition limits the body’s ability to produce fully developed hemoglobin and the proper number of RBCs. As a result, the blood’s oxygen-carrying capability is reduced. cells. This includes removing toxins or discontinuing radiation or chemotherapy. Blood transfusions may also be indicated to help improve the RBC count. In severe cases, bone marrow stem cell transplants can be performed. Pernicious Anemia When the intestines are unable to absorb B12, a vitamin essential for RBC production, the result is pernicious anemia. This condition develops when the stomach stops producing intrinsic factor, a key protein in vitamin B12 absorption. The body may also attack intrinsic factor as a result of a weakened stomach lining or an autoimmune disorder. Pernicious anemia usually develops later in life. On average, diagnosis occurs in patients around 60 years of age. Certain diseases, such as type I diabetes mellitus, Addison’s disease, and chronic thyroiditis, can increase the risk of developing pernicious anemia. Common signs and symptoms of pernicious anemia include a red, swollen tongue pale skin fatigue and shortness of breath. Other symptoms include diarrhea or constipation. Treatment usually consists of vitamin B12 supplements or injections. Anemias Caused by Chronic Disease Chronic illnesses such as rheumatoid arthritis or kidney disease can cause anemia. For example, kidney disease may lower production of the hormone erythropoietin, which regulates RBC production. Inflammatory conditions associated with diseases such as rheumatoid arthritis can affect the bone marrow’s response to erythropoietin, resulting in decreased RBC production. Diseases characterized by chronic infections, such as HIV, tuberculosis, cirrhosis of the liver, and certain cancers, can also cause anemia. Treatment of anemia caused by chronic disease involves diagnosing and resolving the underlying disease. In the short term, blood transfusions may be used as part of the treatment plan for managing anemia. Inherited Anemias Inherited anemias are determined by genetic makeup. In commonly inherited anemias such as sickle cell anemia and thalassemia, a child must receive an anemia gene from both parents to experience symptoms of an inherited anemia. If an anemia gene is received from only one parent, the child will be a carrier but will not experience symptoms.