Understanding Anemias

1. Introduction to Anemias

Anemia is a common hematological condition characterized by a reduction in the number of red blood cells (RBCs) or the hemoglobin concentration within these cells, resulting in decreased oxygen-carrying capacity of the blood. This condition can lead to tissue hypoxia, with varying clinical manifestations ranging from asymptomatic to severe, life-threatening symptoms.

• Definition: Anemia is typically defined as a hemoglobin level lower than the normal range, which varies by age, sex, and altitude of residence. For adult men, anemia is usually defined as a hemoglobin level less than 13.5 g/dL, and for adult women, less than 12 g/dL.

• Overview of Red Blood Cell Production: RBCs are produced in the bone marrow through a process called erythropoiesis. This process is regulated by erythropoietin, a hormone produced by the kidneys in response to hypoxia. The maturation of RBCs requires essential nutrients such as iron, vitamin B12, and folic acid.

• Importance of Hemoglobin: Hemoglobin is the oxygen-carrying protein found in red blood cells. It consists of four globin chains, each bound to a heme group containing iron. Hemoglobin’s primary function is to transport oxygen from the lungs to tissues and carbon dioxide from tissues back to the lungs.

• Classification of Anemia: Anemia can be classified based on the size (mean corpuscular volume, MCV) of the RBCs:

  • Microcytic Anemia: MCV < 80 fL

  • Normocytic Anemia: MCV 80-100 fL

  • Macrocytic Anemia: MCV > 100 fL

2. Microcytic Anemias (MCV < 80 fL)

Microcytic anemias are characterized by the presence of small red blood cells. These anemias typically result from defects in hemoglobin synthesis.

2.1. Thalassemias

• Pathophysiology: Thalassemias are genetic disorders caused by mutations that affect the synthesis of the globin chains of hemoglobin. There are two main types:

  • Alpha Thalassemia: Decreased or absent production of alpha globin chains.

  • Beta Thalassemia: Decreased or absent production of beta globin chains.

• Clinical Manifestations:

  • Alpha Thalassemia: Severity varies depending on the number of affected genes (1-4). Symptoms can range from mild microcytosis to severe anemia and hydrops fetalis.

  • Beta Thalassemia: Major (Cooley’s anemia) presents in early childhood with severe anemia, growth retardation, hepatosplenomegaly, and skeletal deformities.

• Diagnostic Approach:

  • CBC: Low MCV, low MCH (mean corpuscular hemoglobin).

  • Peripheral Smear: Target cells, basophilic stippling.

  • Hemoglobin Electrophoresis: Identifies abnormal hemoglobin patterns; elevated HbA2 in beta-thalassemia.

• Management and Treatment:

  • Mild Forms: Often require no treatment.

  • Severe Forms: Regular blood transfusions, iron chelation therapy, and bone marrow transplant for selected cases.