1. MLAB 1315- Hematology Fall 2007 Keri Brophy-Martinez
Unit 10: Megaloblastic Anemias

2. Megaloblastic Anemias
Megaloblastic anemias are a group of disorders characterized by defective nuclear maturation caused by impaired DNA synthesis. RBC’s are fragile, lifespan is shortened and many die in the bone marrow which causes ↑ LDH. Granulocytes and Thrombocytes are affected as well.
Nuclear replication is slowed down resulting in maturation delays
Macrocytic-normochromic red cells (many macro-ovalocytes)
Granulocytes are hypersegmented
Megakaryoctyes are abnormal resulting in thrombocytopenia

3. Megaloblastic Anemias
Causes
Vitamin B12 (cyanocobalamin) deficiency
Inadequate dietary intake (vegetarians) B12 is found in food of animal origin: red meat, fish, poultry, eggs, dairy products
Malabsorption
Pernicious anemia
Caused by gastric parietal cell atroply which causes decreased secretion of intrinsic factor (IF). IF is necessary for B12 absorption.
Onset is usually after age 50.
Neurologic problems

4. Malabsorption causes (con’t)
Gastrectomy
Blind loop syndrome (bacteria use up the B12)
Fish tapeworm (completes for B12)
Diagnostic test is Schilling Test.

5. Drugs can also cause Vitamin B12 deficiency
Alcohol
Nitrous oxide
Antitubercular drug

6. Folic Acid (Folate) deficiency
Inadequate dietary intake. Folate is found in green leafy vegetables, fruits, dairy products, cereals, liver and kidney.
Poverty
Old age
Alcoholism
Chronic disease
Malabsorption
Tropical sprue
Gluten-sensitive enteropathy
Childhood celiac disease

7. Folic Acid (Folate) deficiency
Increased requirement
Pregnancy
There is increased demand during pregnancy and should be supplemented prior to and during pregnancy. Deficiency during pregnancy can cause neural tube defects in utero.
Infancy
Hematologic diseases that involve rapid cellular proliferation such as sickle cell anemia
Drugs
Methotrexate (chemotherapy drug that is a folate antagonist)
Alcohol
Oral contraceptives
Others

8. Folic Acid (Folate) deficiency
Laboratory tests for megaloblastic anemias
CBC with indices
peripheral smear review
serum folate and B12 levels
RBC folate level
Intrinsic factor antibody, Schilling test, bone marrow examination, liver function studies

9. Treatment of megaloblastic anemia
B12 deficiency
Vitamin therapy
Intramuscular or subcutaneous injections for pernicious anemia to bypass absorption throught the gut.
Folate deficiency

10. Macrocytic Non-Megaloblastic Anemia
MCV doesn’t go as high as in megaloblastic
No hypersegmented neutrophils
Causes:
Chronic liver disease or alcoholism (alcohol has toxic effect on RBC’s)
Macrocytic anemia with elevated retic count. Associated with hemolytic or acute blood loss.
Other