Week 2 - Anemia and Aplastic Anemia Quiz

Chapter 13: Alterations in Oxygen Transport

• Learning Objectives:
  • Identify laboratory tests for anemia and polycythemia
  • Describe anemia's general effects on body systems
  • Differentiate various forms of anemia using history, clinical manifestations, and lab studies
  • Differentiate various forms of polycythemia using history, clinical manifestations, and lab studies
  • Describe treatment for common types of anemia and polycythemia

Anemia

• Definition: A deficit of red blood cells, leading to reduced oxygen-carrying capacity and hypoxia
• Types:
  • Relative: Normal red cell mass, but problems with plasma volume regulation
    • Plasma volume decreases, artificially increasing RBC concentration
  • Absolute: Actual decrease in red blood cell numbers

General Effects of Anemia

• Reduced oxygen-carrying capacity: Leads to tissue hypoxia
• Compensatory mechanisms: Increased heart rate, cardiac output, circulatory rate, and flow to vital organs
• Increased 2,3-DPG: Decreases hemoglobin's affinity for oxygen, promoting oxygen release to tissues

Manifestations of Anemia

• Mild anemia (hemoglobin > 8g/dL): Minimal symptoms
• Moderate/severe anemia (hemoglobin < 8g/dL):
  • Orthostatic hypotension
  • Pallor
  • Tachypnea
  • Headaches/lightheadedness
  • Angina
  • Nighttime leg cramps
  • Tinnitus
  • Fatigue and weakness

Anemia Related to Decreased Red Cell Production

• Aplastic Anemia:

  • Stem cell disorder, reducing hematopoietic tissue in the bone marrow, resulting in fatty marrow replacement (and pancytopenia)
    • Caused by toxic, radiant, or immunologic injury
  • Symptoms: Insidious onset, late symptoms (weakness, fatigue, lethargy, pallor, dyspnea, palpitations, transient murmurs, tachycardia)
  • Pancytopenia and granulocytopenia: Decrease in all blood cells, including neutrophils
  • Treatment: Avoid further toxic exposure, identifying and matching donors for possible bone marrow transplantation, immunosuppressive therapy, or stimulation treatments to promote hematopoiesis and bone marrow regeneration

• Anemia of Chronic Renal Failure:

  • Impaired renal endocrine function, reduces erythropoietin production
  • Symptoms: Decreased RBC count, low HCT and HGB levels
  • Treatment: Dialysis, administration of erythropoietin

• Vitamin B12/Folate Deficiency Anemia:

  • Disrupted DNA synthesis in bone marrow, producing megaloblasts
  • Symptoms: Pernicious anemia due to intrinsic factor deficiency, low RBC, WBC and platelet counts (with increased MCV and megalobastic dysplasia)
  • Treatment: Replacing needed nutritional deficiencies

• Iron Deficiency Anemia:

  • Insufficient iron for hemoglobin synthesis
  • Symptoms: Hypochromic, microcytic RBCs; low MCV, MCH, and MCHC
  • Treatment: Oral ferrous sulfate or intravenous ferric gluconate

Anemia Related to Inherited Disorders of the Red Cell

• Thalassemia:

  • Increased red blood cell destruction (hemolysis), reduced RBC survival rates
    • Presence of mutant genes affecting globin chain production
  • Types: Classified according to deficient polypeptide chain(s)
  • Beta-Thalassemia:
    • Alpha globulin excess
    • Precipitation in RBCs and abnormal hemoglobin synthesis
    • Increased erythropoiesis and bone marrow activity
    • Associated with iron overload, liver toxicity, and bone deformation
    • Treatment: Blood transfusions, splenectomy, chelation therapy and bone marrow transplantation

• Sickle Cell Anemia:

  • Genetically determined defect causing hemoglobin instability, producing sickled red blood cells and causing vascular occlusion
  • Symptoms: Severe anemia, different RBC shapes and sizes.
  • Treatment: Stem cell transplant

• Hereditary Spherocytosis:

  • Defective red blood cell membrane skeleton, altered properties, and metabolism
  • Symptoms: Fragile microspherocytes, increased destruction of spherocytes
  • Treatment: Splenectomy

• Glucose-6-Phosphate Dehydrogenase Deficiency:

  • Genetic disorder affecting RBC membrane, leading to premature destruction.
  • Symptoms: Hemolytic anemia triggered by drugs
  • Treatment: Avoiding drugs that trigger hemolytic episodes, and aggressive infection management

Anemia Related to Extrinsic Red Cell Destruction or Loss

• Hemolytic Disease of the Newborn:

  • Fetal RBCs cross the placenta, creating maternal antibodies that attack the fetus's RBCs (due to incompatibility with maternal blood)
  • Symptoms: Anemia, reticulocytosis, and nucleated RBCs in infant's blood
  • Treatment: Anti-Rh immunoglobulin and possibly in-utero blood transfusions and early delivery

• Antibody-Mediated Drug Reactions:

  • Exposure to a drug triggers destruction and lysis of sensitized RBCs
  • Mechanisms: Hapten mechanisms, neoantigen formation, membrane modification, autoantibody induction
    • Treatment: Identify and discontinue offending medication

• Acute Blood Loss:

  • Trauma or disease-related
  • Symptoms start with 20% blood loss, increasing with continued loss (tachycardia, postural BP drop)
  • Treatment: Blood volume replacement (with crystalloids, colloids, and fresh whole blood)

• Other Extrinsic Abnormalities:

  • Mechanical heart valves (hemolysis)
  • Infections/chemicals
  • Venom from insects/snakes
  • Hypersplenism/splenomegaly (leading to anemia, leukopenia, or thrombocytopenia)

Polycythemia

• Definition: Excess RBCs, leading to increased blood viscosity and hypertension
• Types:

  • Polycythemia Vera: Neoplastic transformation of bone marrow stem cells leading to absolute increase in RBC mass and leukocytosis (along with an increase in WBC and thrombocytopenia/an increase in uric acid due to increased proliferation).

    • Treatment involves reducing blood volume/viscosity(phlebotomy) and possible use of radioactive phosphorus and other chemotherapeutic agents.

  • Secondary Polycythemia: Cause is chronic hypoxemia (leads to increase in erythropoietin production), with an increase in RBC production without an increase in WBCs or platelets.

  • Relative Polycythemia: Spurious increase in RBC production due to dehydration, elevated hematocrit, hemoglobin, and RBC count

• General Treatment: Identify cause and correct it. Use fluid therapy sometimes and/or phlebotomy to decrease cardiovascular workload.

Transfusion Therapy

• Medical indications: Restoration of oxygen-carrying capacity, blood volume, hemostasis and/or leukocyte function
• Donor testing: Ensuring safety of blood products, specific pre transfusions testing to ensure blood components are safe and compatible for the patient