Hematologic Disorders



Hematologic Disorders





ANEMIA

Anemia is a condition associated with lower than normal levels of erythrocytes in the blood. There are several types of anemia, including aplastic, iron deficiency, and pernicious.


Causes


Aplastic Anemia



  • Congenital or acquired


  • Autoimmune reactions or other severe disease (hepatitis)


  • Drugs, radiation, and toxic agents


Iron Deficiency Anemia



  • Inadequate iron intake or iron malabsorption


  • Blood loss


  • Pregnancy, which diverts maternal iron to fetus


  • Intravascular hemolysis-induced hemoglobinuria or paroxysmal nocturnal hemoglobinuria


  • Trauma by prosthetic heart valve or vena cava filters


Pernicious Anemia



  • Vitamin B12 deficiency due to lack of intrinsic factor in stomach lining


  • Genetic predisposition and age over 60


  • Immunologically related disorder


  • Partial gastrectomy







SICKLE CELL ANEMIA

Acongenital hemolytic anemia that occurs primarily, but not exclusively, in blacks, sickle cell anemia results from a defective hemoglobin molecule (Hb S) that causes RBCs to become sickle-shaped. Such cells clog capillaries and impair circulation, resulting in chronic ill health (fatigue, dyspnea on exertion, swollen joints), periodic crises, long-term complications, and early death.

If both parents are carriers of sickle cell trait (or another hemoglobinopathy), each child has a 25% chance of developing sickle cell anemia. Approximately 1 out of every 500 blacks has sickle cell anemia. The defective Hb S-producing gene may have persisted because, in areas where malaria is endemic, the heterozygous sickle cell trait provides resistance to malaria and is actually beneficial.



Causes



  • Homozygous inheritance of the gene that produces Hb S


  • Heterozygous inheritance of this gene results in sickle cell trait, which is usually asymptomatic







THALASSEMIA

Thalassemia, a group of hereditary hemolytic anemias, is characterized by defective synthesis in the polypeptide chains of the protein component of Hb. RBC synthesis is also impaired.

Thalassemias are most common in people of Mediterranean ancestry (especially Italian and Greek, who develop the form called beta-thalassemia). People whose ancestors originated in Africa, southern China, southeast Asia, and India develop the form called alpha-thalassemia, which reflects deletion of one or more of four Hb genes. Prognosis varies with the number of deleted genes.

In beta-thalassemia, the most common form of this disorder, synthesis of the beta-polypeptide chain is defective. It occurs in three clinical forms: major, intermedia, and minor. The severity of the resulting anemia depends on whether the patient is homozygous or heterozygous for the thalassemic trait. The prognosis varies:



  • thalassemia major — patients seldom survive to adulthood


  • thalassemia intermedia — children develop normally into adulthood; puberty usually delayed


  • thalassemia minor — normal life span.


Causes


Beta-Thalassemia



  • Thalassemia major or intermedia — homozygous inheritance of a partially dominant autosomal gene


  • Thalassemia minor — heterozygous inheritance of the same gene


Alpha-Thalassemia



  • Deletion of one or more of four genes







POLYCYTHEMIA VERA

Polycythemia vera is a chronic disorder characterized by increased RBC mass, erythrocytosis, leukocytosis, thrombocytosis, elevated Hb level, and low or normal plasma volume. This disease is also known as primary polycythemia, erythremia, or polycythemia rubra vera. It occurs most commonly among Jewish males of European descent.



Causes

Unknown, but probably related to a clonal stem cell defect. Nearly all patients have a mutation on the JAK2 gene, which results in altered signal within the Janus kinase pathway.

Sep 22, 2018 | Posted by in ANATOMY | Comments Off on Hematologic Disorders
Premium Wordpress Themes by UFO Themes
%d bloggers like this: