Anemias and Red Blood Cell Problems

Anemias and Red Blood Cell Problems

Objectives

  • Understand the normal function of red blood cells.

  • Recognize abnormal levels of hemoglobin and hematocrit.

  • Know the different types of anemia.

  • Understand:
      - The signs and symptoms of anemia and the reasons for their occurrence.
      - The causes of different types of anemias as well as treatment options.

  • Understand the pathophysiology behind polycythemia.

Hemoglobin

  • Hemoglobin structure: Each chain contains a heme unit with iron at the center.

  • Functions:
      - Reversibly binds oxygen and carbon dioxide for transport.
      - Hemoglobin can bind to other substances due to the protein structure.

Anatomy of Anemia

  • Anemia: A condition characterized by a decrease in red blood cells (RBCs).

  • Each red blood cell contains several hundred hemoglobin molecules responsible for oxygen transport:
      - Oxygen binds to the heme on the hemoglobin molecule:

      HbO2HbO_2, HbO4HbO_4, HbO6HbO_6, HbOgHbOg.

Diseases of Red Blood Cells

  • Diseases can relate to either:
      - Quantity: Decreased number of RBCs.
      - Quality: Abnormal structure or function of hemoglobin.

  • Regardless of the cause, all diseases of RBCs lead to:
      - Less oxygen transport to tissues, resulting in impaired cellular and organ functions

Hematocrit Analysis

  • Centrifugation of blood into hematocrit tube:
      - Layers observed: Plasma, White blood cells (WBCs), and platelets, Red blood cells (RBCs).
      - Hematocrit percentage indicates the proportion of RBCs in the blood.

Comparison: Anemia vs. Polycythemia

  • Normal Hematocrit Range: 37% - 47%

  • Anemia: Hematocrit = 30% (indicates decreased RBCs)

  • Polycythemia: Hematocrit = 70% (indicates increased RBCs due to dehydration or other causes)

Causes of Anemia

  • Multiple causes include:
      - Inflammation
      - Neoplasia
      - Chronic disease
      - Marrow damage
      - Iron deficiency
      - Acute bleeding
      - Maturation disorders
      - Hemolytic anemias

Symptoms of Anemia

  • Common symptoms include:
      - Pallor
      - Fatigue
      - Lethargy
      - Malaise
      - Depression
      - Cognitive impairment: Poor memory and cognition.
      - Reduced exercise tolerance, shortness of breath
      - Weakness, dizziness, fainting, low blood pressure, heart palpitations, rapid heart rate, chest pain including angina and heart attack.
      - Worsening congestive heart failure (CHF)
      - Impaired libido and impotence
      - Symptoms can indicate the severity of anemia.

Clinical Manifestations of Anemia

  • Anemia results in a decreased oxygen carrying capacity:
      - Mild cases may present no symptoms.
      - Moderate cases can cause fatigue, weakness, tachycardia, dyspnea.
      - Severe cases will increase heart and respiratory rate, hypotension, pallor, and faintness.

Effects of Anemia on Body Functions

  • Oxygen to muscles: Decrease in oxygen to muscles leads to weakness.

  • Energy production: Reduced energy production increases fatigue.

  • Peripheral circulation: Blood is redistributed to manage pallor.

  • Cardiac output may decrease, causing increased heart rate and palpitations.

  • Secretion of erythropoietin increases, leading to bone pain.

  • Hypoxia in cardiac muscle can cause chest pain and heart failure.

Types of Anemia

  • Classification based on hemoglobin content:
      - Decreased number of circulating erythrocytes
      - Abnormal hemoglobin (e.g., Sickle Cell Disease)
      - Loss of iron and production anomalies
      - Increased destruction of RBCs

Abnormal Hemoglobin Disorders

  • Sickle Cell Disease:
      - Red blood cells adopt an abnormal sickle shape leading to compromised blood flow and decreased hemoglobin functionality.

Iron Deficiency Anemia

  • Most Common Type of Anemia:
      - Etiologies include decreased intake, decreased absorption, increased demand, and excessive loss (e.g., GI bleeding).
      - Iron is critical for hemoglobin production:

Clinical Manifestations of Iron Deficiency

  • Symptoms include those of anemia, as well as:
      - Epithelial atrophy
      - Brittle hair and nails (koilonychia)
      - Glossitis, mouth sores, dysphagia (difficulty swallowing)
      - PICA: Craving non-food items, particularly ice (Pagophagia).

Vitamin B12 and Folate Deficiency

  • Involved in normal DNA synthesis critical for erythrocyte maturation.

  • Folate Deficiency:
      - Commonly related to decreased intake, alcoholism, or pregnancy.

  • Vitamin B12 Deficiency:
      - Often due to pernicious anemia; impaired absorption due to lack of intrinsic factor.
      - Symptoms can be similar to those of general anemia but also include neurological issues (e.g., memory loss, confusion).

Aplastic Anemia

  • Primary condition involving the failure of bone marrow stem cells.

  • Can be congenital or acquired due to exposure to toxins, radiation, autoimmune mechanisms, or infectious complications.

Increased Destruction of RBCs

  • Acquired Hemolytic Anemia:
       - Reflects premature destruction of RBCs caused by external factors.
       - Presents with immune complexes and mild jaundice.

Blood Loss Anemia

  • Results from acute or chronic blood loss:
      - Acute blood loss can lead to vital consequence depending on the volume lost.

Pharmacotherapy of Anemia

  • Use of Erythropoiesis Stimulating Agents (e.g., epoetin alfa).

  • Nutritional therapy with iron, vitamin B12, and folic acid supplementation.

Polycythemia Overview

  • Relative Polycythemia: Dehydration leads to elevated RBC counts.

  • Primary Polycythemia: Polycythemia vera linked to neoplastic disease.

  • Secondary Polycythemia: Adaptive response related to chronic hypoxia.

Clinical Manifestations of Polycythemia

  • Increased viscosity can lead to hypertension, headaches, and increased thromboembolic events.

References

  • Acknowledge contributions and resources utilized in compiling this information.