MLAB 1315- HematologyFall 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 Vitamin therapy

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