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BIOC33H3 (127)

Hematologic Problems

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Biological Sciences
Stephen Reid

Chapter 31: Hematologic Problems ANEMIA  Anemia is a deficiency in the number of erythrocytes (red blood cells [RBCs]), the quantity of hemoglobin, and/or the volume of packed RBCs (hematocrit), which can lead to tissue hypoxia.  Hemoglobin (Hb) levels are often used to determine the severity of anemia.  Correcting the cause of the anemia is ultimately the goal of therapy.  Interventions may include blood or blood product transfusions, drug therapy, volume replacement, oxygen therapy, dietary modifications, and lifestyle changes. Anemia Caused By Decreased Erythrocyte Production Iron-Deficiency Anemia  Iron-deficiency anemia may develop from inadequate dietary intake, malabsorption, blood loss, or hemolysis. Also, pregnancy contributes to iron deficiency because of the diversion of iron to the fetus for erythropoiesis, blood loss at delivery, and lactation.  The main goal of collaborative care for iron-deficiency anemia is to treat the underlying disease causing reduced intake (e.g., malnutrition, alcoholism) or absorption of iron. In addition, efforts are directed toward replacing iron with dietary changes or supplementation.  It is important for a nurse to recognize groups of individuals who are at an increased risk for the development of iron-deficiency anemia. These include premenopausal and pregnant women, persons from lower –class socioeconomic backgrounds, older adults, and individuals experiencing blood loss. Thalassemia  Thalassemia is a group of diseases that has an autosomal-recessive genetic basis that involves inadequate production of normal hemoglobin.  An individual with thalassemia may have a heterozygous or homozygous form of the disease, based on the number of thalassemic genes the individual has.  Thalassemia minor requires no treatment because the body adapts to the reduced level of normal hemoglobin.  The symptoms of thalassemia major are managed with blood transfusions or exchange transfusions in conjunction with IV deferoxamine to reduce the iron overloading (hemochromatosis) that occurs with chronic transfusion therapy. MEGALOBLASTIC ANEMIAS  Megaloblastic anemias are a group of disorders caused by impaired DNA synthesis and characterized by the presence of large RBCs.  Macrocytic (large) RBCs are easily destroyed because they have fragile cell membranes.  Two common forms of megaloblastic anemia are cobalamin deficiency and folic acid deficiency. o Cobalamin (vitamin B 12deficiency is most commonly caused by pernicious anemia, which results in poor cobalamin absorption through the GI tract. Parenteral or intranasal administration of cobalamin is the treatment of choice. o Folic acid (folate) is required for DNA synthesis leading to RBC formation and maturation and therefore can lead to megaloblastic anemia. Folic acid deficiency is treated by replacement therapy. Aplastic Anemia  Aplastic anemia is a disease in which the patient has peripheral blood pancytopenia (decrease of all blood cell types) and hypocellular bone marrow.  Management of aplastic anemia is based on identifying and removing the causative agent (when possible) and providing supportive care until the pancytopenia reverses. Anemia Caused By Blood Loss Acute Blood Loss  Acute blood loss occurs as a result of sudden hemorrhage.  Causes of acute blood loss include trauma, complications of surgery, and conditions or diseases that disrupt vascular integrity.  Collaborative care is initially concerned with replacing blood volume to prevent shock and identifying the source of the hemorrhage and stopping the blood loss. Chronic Blood Loss  The sources of chronic blood loss are similar to those of iron-deficiency anemia (e.g., bleeding ulcer, hemorrhoids, menstrual and postmenopausal blood loss).  Management of chronic blood loss anemia involves identifying the source and stopping the bleeding. Supplemental iron may be required. Anemia Caused By Increased Erythrocyte Destruction (Hemolytic Anemia) SICKLE CELL DISEASE  Sickle cell disease is a group of inherited, autosomal recessive disorders characterized by the presence of an abnormal form of hemoglobin in the erythrocyte.  The major pathophysiologic event of this disease is the sickling of RBCs. Sickling episodes are most commonly triggered by low oxygen tension in the blood.  With repeated episodes of sickling there is gradual involvement of all body systems, especially the spleen, lungs, kidneys, and brain.  Collaborative care for a patient with sickle cell disease is directed toward alleviating the symptoms from the complications of the disease and minimizing end target-organ damage. There is no specific treatment for the disease. Acquired Hemolytic Anemia  Extrinsic causes of hemolysis can be separated into three categories: (1) physical factors, (2) immune reactions, and (3) infectious agents and toxins.  Physical destruction of RBCs results from the exertion of extreme force on the cells.  Antibodies may destroy RBCs by the mechanisms involved in antigen-antibody reactions.  Infectious agents foster hemolysis in four ways: (1) by invading the RBC and destroying its contents, (2) by releasing hemolytic substances, (3) by generating an antigen-antibody reaction, and (4) by contributing to splenomegaly as a means of increasing removal of damaged RBCs from the circulation. HEMOCHROMATOSIS  Hemochromatosis is an autosomal recessive disease characterized by increased intestinal iron absorption and, as a result, increased tissue iron deposition.  The goal of treatment is to remove excess iron from the body and minimize any symptoms the patient may have. POLYCYTHEMIA  Polycythemia is the production and presence of increased numbers of RBCs. The increase in RBCs can be so great that blood circulation is impaired as a result of the increased blood viscosity and volume.  Treatment is directed toward reducing blood volume/viscosity and bone marrow activity. Phlebotomy is the mainstay of treatment. THROMBOCYTOPENIA 9  Thrombocytopenia is a reduction of platelets below 150,000/μl (150 × 10 /L).  Platelet disorders can be inherited, but the vast majority of them are acquired. The causes of acquired disorders include autoimmune diseases, increased platelet consumption, splenomegaly, marrow suppression, and bone marrow failure.  The most common acquired thrombocytopenia is a syndrome of abnormal destruction of circulating platelets termed immune thrombocytopenic purpura (ITP). Multiple therapies are used to manage the patient with ITP, such as corticosteroids or splenectomy.  One of the risks associated with the broad and increasing use of heparin is the development of the life-threatening condition called heparin-induced thrombocytopenia and thrombosis syndrome (HITTS). Heparin must be discontinued when HITTS is first recognized, which is usually if the patient’s platelet count has fallen 50% or more from its baseline or if a thrombus forms while the patient is on heparin therapy.  For the nurse, the overall goals are that the patient with thrombocytopenia will (1) have no gross or occult bleeding, (2) maintain vascular integrity, and (3) manage home care to prevent any complications related to an increased risk for bleeding. HEMOPHILIA AND VON WILLEBRAND DISEASE  Hemophilia is a sex-linked recessive genetic disorder caused by defective or deficient coagulation factor. The two major forms of hemophilia, which can occur in mild to severe forms, are hemophilia A and hemophilia B.  Von Willebrand disease is a related disorder involving a deficiency of the von Willebrand coagulation protein.  Replacement of deficient clotting factors is the primary means of supporting a patient with hemophilia. In addition to treating acute crises, replacement therapy may be given before surgery and before dental care as a prophylactic measure.  Home management is a primary consideration for the patient with hemophilia because the disease follows a progressive, chronic course.  The patient with hemophilia must be taught to recognize disease-related problems and to learn which problems can be resolved at home and which require hospitalization. DISSEMINATED INTRAVASCULAR COAGULATION  Disseminated intravascular coagulation (DIC) is a serious bleeding and thrombotic disorder.  It results from abnormally initiated and accelerated clotting. Subsequent decreases in clotting factors and platelets ensue, which may lead to uncontrollable hemorrhage.  DIC is always caused by an underlying disease or condition. The underlying problem must be treated for the DIC to resolve.  It is important to diagnose DIC quickly, stabilize the patient if needed (e.g., oxygenation, volume replacemen
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