Pernicious Anemia

  1. General information
    1. Chronic progressive, macrocytic anemia caused by a deficiency of intrinsic factor; the result is abnormally large erythrocytes and hypochlorhydria (a deficiency of hydrochloric acid in gastric secretions)
    2. Characterized by neurologic and GI symptoms; death usually results if untreated
    3. Lack of intrinsic factor is caused by gastric mucosal atrophy (possibly due to heredity, prolonged iron deficiency, or an autoimmune disorder); can also result in clients who have had a total gastrectomy if vitamin B12 not administered
    4. Usually occurs in men and women over age 50, with an increase in blue-eyed persons of Scandinavian descent
    5. Pathophysiology
      1. Intrinsic factor is necessary for the absorption of vitamin B12 into the small intestine.
      2. B12 deficiency diminishes DNA synthesis, which results in defective maturation of cells (particularly rapidly dividing cells such as blood cells and GI tract cells).
      3. B12 deficiency can alter structure and function of peripheral nerves, spinal cord, and the brain.
  2. Medical management
    1. Drug therapy
      1. Vitamin B12 injections: monthly maintenance
      2. Iron preparations (if Hgb level inadequate to meet increased numbers of erythrocytes)
      3. Folic acid
        1. controversial
        2. reverses anemia and GI symptoms but may intensify neurologic symptoms
        3. may be safe if given in small amounts in addition to vitamin B12
    2. Transfusion therapy
  3. Assessment findings
    1. Anemia, weakness, pallor, dyspnea, palpitations, fatigue
    2. GI symptoms: sore mouth; smooth, beefy, red tongue; weight loss; dyspepsia; constipation or diarrhea; jaundice
    3. CNS symptoms; tingling, paresthesias of hands and feet, paralysis, depression, psychosis
    4. Laboratory tests
      1. Erythrocyte count decreased
      2. Blood smear: oval, macrocytic erythrocytes with a proportionate amount of Hgb
      3. Bone marrow
        1. increased megaloblasts (abnormal erythrocytes)
        2. few normoblasts or maturing erythrocytes
        3. defective leukocyte maturation
      4. Bilirubin (indirect): elevated unconjugated fraction
      5. Serum LDH elevated
      6. Positive Schilling test
        1. measures absorption of radioactive vitamin B12 both before and after parenteral administration of intrinsic factor
        2. definitive test for pernicious anemia
        3. used to detect lack of intrinsic factor
        4. fasting client is given radioactive vitamin B12 by mouth and nonradioactive vitamin B12 IM to saturate tissue binding sites and to permit some excretion of radioactive vitamin B12 in the urine if it is absorbed
        5. 24-48 hour urine collection is obtained; client is encouraged to drink fluids
        6. if indicated, second stage Schilling test performed 1 week after first stage. Fasting client is given radioactive vitamin B12 combined with human intrinsic factor and test is repeated.
      7. Gastric analysis: decreased free hydrochloric acid
      8. Large numbers of reticulocytes in the blood following parenteral vitamin B12 administration
  4. Nursing interventions
    1. Provide a nutritious diet high in iron, protein, and vitamins (fish, meat, milk/milk products, and eggs).
    2. Avoid highly seasoned, coarse, or very hot foods if client has mouth sores.
    3. Provide mouth care before and after meals using a soft toothbrush and nonirritating rinses.
    4. Bed rest may be necessary if anemia is severe.
    5. Provide safety when ambulating (especially if carrying hot items, etc.)
    6. Provide client teaching and discharge planning concerning
      1. Dietary instruction
      2. Importance of lifelong vitamin B12 therapy
      3. Rehabilitation and physical therapy for neurologic deficits, as well as instruction regarding safety