Anemias and Red Blood Cell Problems Practice Flashcards

Anemias and Red Blood Cell Problems

Objectives

Understand:
* Normal function of red blood cells.
Recognize:
* Abnormal levels of hemoglobin and hematocrit.
Know:
  * The different types of anemia.
  * Signs and symptoms of anemia and their occurrences.
  * Causes of different types of anemia and treatment options.
Understand:
* Pathophysiology behind polycythemia.

Hemoglobin

Each hemoglobin chain contains:
  - Heme unit with iron at the center.
  - Ability to reversibly bind oxygen and carbon dioxide for transport.
  - Capability to bind other substances due to its protein structure.

Anemia

Definition:
- Condition characterized by a lower than normal amount of red blood cells or hemoglobin in the blood, impacting oxygen transport.
Hemoglobin content in RBCs:
  - RBCs contain several hundred hemoglobin molecules that transport oxygen bound to heme (on the hemoglobin molecule).
  - Notable hemoglobin equations include.
    - $ext{HbO}_2$ - Oxygenated hemoglobin
    - $ext{HbO}_4$ - Further oxygenated hemoglobin.
    - $ext{HbO}_6$ - Yet higher saturation.

Diseases of Red Blood Cells

Related to two key factors:
- Quantity: Total number of RBCs.
- Quality: Functionality or shape of RBCs.
All diseases lead to a reduction in oxygen transportation to tissues, affecting cellular function.

Hematocrit and Its Measurement

Process:
  - Centrifuge blood in a hematocrit tube to separate components by density.
  - Hematocrit scale indicates proportions as follows:
    - Plasma (top layer).
    - Formed elements (middle layer): white blood cells and platelets form the buffy coat.
    - Red blood cells at the bottom of the tube.
Normal Hematocrit Levels:
  - Varies; normal ranges are approximately 37-52%.
  - Hematocrit values indicative of conditions:
    - Anemia: Decreased hematocrit (e.g., 30%).
    - Polycythemia: Increased hematocrit (e.g., 70%).

Causes of Anemia

Consider multiple factors:
  - Inflammation.
  - Neoplasia.
  - Chronic disease.
  - Marrow damage.
  - Iron deficiency.
  - Acute bleeding.
  - Maturation disorders.
  - Hemolytic anemias.

Symptoms of Anemia

Clinical manifestations include but are not limited to:
  - Pallor of the skin.
  - Fatigue and lethargy.
  - Malaise and generalized depression.
  - Impaired cognition and memory.
  - Reduced exercise tolerance.
  - Shortness of breath and weakness.
  - Changes in skin tone (e.g., coldness, leg cramps).
  - Dizziness, fainting, low blood pressure.
  - Heart palpitations, rapid heart rate, chest pain, angina, heart attacks.
  - Worsening congestive heart failure (CHF).
  - Impaired libido and insomnia.
  - Enlarged spleen.
  - Headaches.

Anemia Clinical Manifestations

Decreased oxygen carrying capacity:
  - Mild Anemia: May show few if any symptoms.
  - Moderate Anemia: Symptoms include:
    - Fatigue, weakness, tachycardia, dyspnea.
  - Moderate-Severe Anemia: Increased heart rate and respiratory rate, hypotension, pallor, faintness, cardiovascular problems.
  - Speed of decrease in hemoglobin can affect severity of symptoms.

Impacts on Body Functions Due to Anemia

Oxygen to muscles: Decreased, leading to weakness.
Energy production: Decreased, causing fatigue.
Peripheral circulation: Compensatory blood redistribution leads to pallor.
Cardiac output: Increases with compensatory tachycardia/palpitations.
Secretion of erythropoietin: Increased, leading to additional bone pain.
Overall oxygenation: Decreased, leading to dyspnea and increased respiratory rate.

Types of Anemia

Decreased number of circulating erythrocytes.
Decreased Hemoglobin Content.
   - Caused by:
     - Iron deficiency: Iron is essential for hemoglobin production.
     - Vitamin B12 or Folate deficiency: Critical for DNA synthesis.
Abnormal Hemoglobin types, such as Sickle Cell Disease and Thalassemia.
Loss of iron or key nutrients due to various causes.

Specific Anemias

Sickle Cell Disease

Characterized by:
  - Abnormally shaped (sickle-shaped) RBCs due to Hemoglobin S.
  - Inability to bind oxygen effectively.
  - Potential complications include blockage in blood flow, leading to pain and risk of organ damage.

Iron Deficiency Anemia

Most common anemia type:
  - Etiologies:
    - Decreased intake.
    - Decreased absorption.
    - Increased demand (e.g., rapid growth).
    - Excessive blood loss (e.g., GI bleeding, menstruation).
  - Iron is essential for hemoglobin formation; consequently, when iron levels are low, hemoglobin production is compromised.

Clinical Manifestations of Iron Deficiency

Common symptoms align with anemia and include:
  - Epithelial atrophy: Including symptoms like brittle hair and nails (koilonychia).
  - Glossitis: Inflammation of the tongue.
  - Pica: Compulsion to eat non-food substances (e.g., pagophagia - craving ice).

Vitamin B12 and Folic Acid Deficiency

Normal pathway: Allows for DNA synthesis and maturation of all cells, including erythrocytes.
Alternate pathway: Observes deficiencies that lead to unbalanced cell growth and megaloblastic anemia.
Vitamin B12 deficiency may cause:
- Glossitis, depression, confusion, and neurologic effects due to inadequate DNA synthesis.
- Intrinsic factor (IF): Required for B12 absorption; loss typically leads to pernicious anemia.
Folic Acid Deficiency: Occurs due to decreased intake, alcoholism, or higher physiological demands (e.g., pregnancy).

Anemia of Chronic Disease

Linked to impaired erythropoietin production due to chronic kidney disease.
Represents a direct correlation between hemoglobin/hematocrit levels and degree of kidney insufficiency.

Aplastic Anemia

Defined as a primary condition of bone marrow stem cells where production of blood cells is severely diminished.
Classified into congenital and acquired types.
Associated complications include reduced immunity due to low levels of leukocytes.
Possible causative factors:
- Idiopathic reasons, toxins, radiation exposure, autoimmune mechanisms, or viral infections (e.g., hepatitis, mononucleosis).

Increased Destruction of RBCs

Caused by abnormal hemoglobin states (e.g., Sickle cell anemia)
Key Indicators:
- Low hemoglobin levels with potential jaundice, hemoglobinuria, and decreased haptoglobin.

Blood Loss Anemia

Results from significant or occult bleeding, categorized by acute and chronic blood loss.
The rate of blood loss drastically affects symptom manifestation:
- Acute blood loss: Rapid and can lead to shock depending on percentage lost.
- Chronic blood loss: Occurs over time and requires careful monitoring of organ function.

Pharmacotherapy of Anemia

Erythropoiesis Stimulating Agents:
- Epoetin alfa (Epogen, Procrit): Mimics human erythropoietin, given SubQ; noted for significant safety implications.
Oral Iron supplements:
- Ferrous sulfate: Common treatment for iron deficiency; several considerations on absorption affected by food or antacids.
Parenteral Iron:
- Iron Dextran: Used when oral iron is ineffective; carries risks of anaphylaxis based on individual tolerance.
Vitamin B12 and Folic Acid supplementation: Essential for preventing deficiencies and ensuring proper erythropoiesis.

Types of Polycythemia

Relative Polycythemia:
- Isolated decrease in plasma volume; conditions like severe dehydration can elevate Hgb and Hct levels.
Primary Polycythemia (Polycythemia Vera):
- Neoplastic disease characterized by the overproduction of blood cells.
Secondary Polycythemia:
- Compensatory response to tissue hypoxia (e.g., in chronic lung disease or high altitude).

Clinical Manifestations of Polycythemia

Increased blood viscosity and volume leading to:
- Hypertension, headaches, dizziness, dusky red coloring, possible cyanosis, and pruritus.
Complications arising from poor blood flow include thrombosis and ischemic events.

References

Academic Contributors:
- Thanks to Lynn Kelso, APRN, FCCM, FAANP.
Related Literature:
- Capriotti, T. M., & Frizzell, J. P. (2015). Pathophysiology: Introductory concepts and clinical perspectives. FA Davis Company.