Erythrocytes : Pathophysiology

• Normochromic


  normal RBC color
• Normocytic


  normal RBC size
• Microcytic


  smaller than normal
• Macrocytic


  bigger than normal
• Hypochromic


  paler
• Hemolytic


  raised cell destruction rate
• Megaloblastic


  large & immature
• Anemia


  - inability of the blood to carry enough oxygen

  - due to low hemoglobin levels

  - sometimes due to production of faulty hemoglobin
• Anemia is classified based on _


  Anemia is classified based onthe cause
• Anemia: Causes (2)


  1. Production of insufficient or defective erythrocytes

  2. Blood loss or excessive erythrocyte breakdown
• Iron-deficiency anemia


  - most common anemia

  ☆ daily iron requirement

  ☆ RBC characteristics
• Daily iron requirement: Men


  ~1-2 mg
• Daily iron requirement: Women


  3 mg

  - counter blood loss in menstruation

  - needs of growing fetus in pregnancy
• Daily iron requirement: Children


  Children require more iron than adults to meet their growth requirements
• Iron-deficiency Anemia: RBC characteristics


  - microcytic

  - hypochromic

  - have less hemoglobin
• Hemoglobin: Below Normal


  MCH (mean cell hemoglobin) < 27 pg/cell
• Severe Anemia: Hemoglobin level


  Hb < 9 g/100 mL blood
• Iron-deficiency Anemia: Etiology (3)


  1. Deficient intake

  2. Unusually high iron requirements

  3. Poor absorption (malabsorption) from the alimentary tract
• Deficient intake: Example

  very restrictive, unbalanced diet

  - not getting daily iron requirements
• Unusually high iron requirements: Example


  Pregnancy

  - to support fetus growth
• Poor absorption (malabsorption) from the alimentary tract: Example

  Taking excess antacids

  - iron absorption is dependent on acid environment of stomach

  - stomach pH increases = iron may not be absorbed properly
• Vitamin B9


  Folic acid (Folate)
• Folic Acid & Vitamin B12 Deficiency Anemia


  - impairs erythrocyte maturation

  - rate of DNA & RNA synthesis is reduced

  - delayed cell division = more time for cell enlargement
• Folic Acid & Vitamin B12 Deficiency Anemia: RBC Characteristics


  - megaloblasts

  - nucleated (due to improper maturation)

  - fragile

  
  

  MCV > 94 L

  Hb content: normal or raised

  lifespan: 40-50 days
• Folic Acid & Vitamin B12 Deficiency Anemia: Causes (2)

  1. Depressed production

  2. Early lysis
• Pernicious anemia


  - most common form of B12 deficiency anemia

  - autoimmune disease

  - associated with other autoimmune disorders, specifically thyroid disease

  - common in females & the ederly
• Vitamin B12


  - Cobalamin

  - available in animal-derived food products: dairy, meat, eggs

  - stored in the liver
• Vitamin B12 deficiency is rare, except in _


  Vitamin B12 deficiency is rare, except instrict vegans
• Vitamin B12 Deficiency: Causes (3)

  1. Gastrectomy

  2. Chronic gastritis, malignant disease, ionizing radiation

  3. Malabsorption - e.g., Crohn's disease
• Vitamin B12 Deficiency Anemia: Complications (2)

  1. irreversible neurological damage: commonly in the spinal cord

  2. mucosal abnormalities; e.g. glossitis - reversible
• Folic acid deficiency anemia

  Megaloblastic anemia
• Megaloblastic Anemia


  - identical to that seen in vitamin B12 deficiency

  - not associated with neurological damage
• Megaloblastic Anemia: Etiology (3)


  1. Dietary deficiency.

  2. Malabsorption from the jejunum

  3. Interference with folate metabolism
• Dietary deficiency: Examples (4)

  1. in infants if there is a delay in establishing a mixed diet

  2. in alcoholism

  3. in anorexia

  4. in pregnancy
• Malabsorption from Jejunum: Causes (3)

  1. Celiac disease

  2. Anticonvulsant drugs

  3. Tropical sprue
• Interference with folate metabolism: Causes (2)

  1. Cytotoxic Drugs

  2. Anticonvulsant drugs
• Aplastic (hypoplastic) Anemia

  - due to bone marrow failure

  - RBC numbers are reduced

  - leukopenia & thrombocytopenia are also likely
• Leukopenia

  low WBC count
• Thrombocytopenia

  low platelet count
• Pancytopenia

  - all three cell types are low

  - occasionally inherited