Ch. 11 Megaloblastic Anemias
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- Associated with: Vitamin B12 or Folic Acid deficiency.
- Nutritional deficiency or malabsorption
- B12 and Folic Acid are needed for DNA synthesis. Cause delayed nuclear maturation.
Asynchronous cell maturation:
- Mature cytoplasm
- Immature nucleus
- Weird looking: Nucleus and cytoplasm don't match
Causes of Vitamin B12 Deficiencies:
- Increased B12 utilization
- Malabsorption of B12 from the GI tract.
- Nutritional deficiency.
- Pernicious Anemia (PA)
Causes of Folic Acid Deficiency:
- GI malabsorption
- Increased utilization (Pregnancy, leukemias)
- Antimetabolites (drugs that inhibit folic acid)
B12 deficiencies median age at diagnosis:
60 years old
Folic acid deficiencies most common in:
Females over 30
- Absorption requires GI tract binding proteins.
- Most important binding proteins is Intrinsic Factor (IF).
- glycoprotein secreted by stomach parietal cells.
- Stomach acid promotes formation of B12-IF complex.
- Transcobalamin II (plasma protein) transports B12 to liver and tissues.
B12 and Folic Acid Deficiencies:
- Associated with: poor diet
- newborn neural tube defects
- Pernicious Anemia
Pernicious Anemia caused by:
If no intrinsic factor=NO B12
- Decreased Intrinsic Factor
- Gastric atrophy
- Antibodies against IF
- Antibodies against parietal cells
Lab of B12 and Folic Acid Deficiencies:
- B12 and Folic acid deficiencies have same effects.
- Decreased=RBC, HGB, HCT, WBC, PLTs, B12, Folic Acid
- Increased= MCV (oval macrocytes)
- Aniso, Poik, Ovalocytes, NRBCs, Basophillic stippling, HJ bodies
- Hyperseg neutrophils
- Increased plasma LDH enzyme (from hemolyzed RBCs)
- Macrocytic: MCV >96
- Megaloblastic: specific macrocytic anemia with asynchronous nuclear-cytoplasmic maturation
- Megaloblastic anemias associated with B12/Folic acid deficiency.
- Macrocytic Non-megaloblastic anemias seen in liver disease.
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