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

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

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

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

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

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

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

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

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

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