Anemia Overview

Question 1

Anemia Definition

Answer 1

Anemia is operationally defined as a reduction in one or more of the major RBC measurements:

Hemoglobin concentration, hematocrit, or RBC count

Keep in mind these are all concentration measures

Question 2

Key test for production vs destruction anemia

Answer 2

Increased reticulocytes (greater than 2-3% or 100,000/mm3 total) are seen in blood loss and hemolytic processes, although up to 25% of hemolytic anemias will present with a normal reticulocyte count due to immune destruction of red cell precursors. 
Retic counts are most helpful if extremely low (s hematocrit. When the hematocrit is lower reticulocytes are released earlier from the marrow so one can adjust for this phenomenon.

Question 3

MCV>100

Answer 3

Macrocytic
B12, Folic acid deficiency (ham and eggs)
Drugs that impair DNA synthesis (AZT, chemotherapy, alcohol, azathioprine)

Question 4

MCV 80-100

Answer 4

Normocytic
Anemia of chronic disease
Mixed deficiencies
Renal failure

Question 5

MCV < 80

Answer 5

Microcytic
Iron deficiency
Thalassemia trait
Anemia of chronic disease (30-40%)
Sideroblastic anemias

Question 6

B12/Folate Deficiency

Answer 6

Etiology:
Anemia– Vitamin B12 and folate are needed for DNA synthesis deoxyuridate to thymidylate , including RBC precursors
Deficiency
B12 - Dietary intake (rare), decreased gastric secretion of intrinsic factor
Folate– Poor dietary intake  EtOH, malabsorption, increased demand (pregnancy, hemolytic anemias)

Dx:
Smear: Macrocytic (High MCV) RBCs, +/- hypersegmented neutrophils, +/- modest neutropenia, but…
B12
Low serum B12, elevated serum methylmalonic acid levels
Anti-IF Abs, Schilling test (?), PA accounts for 75%
Folate
Serum folate level– can normalize with a single good meal

Tx:
B12 deficiency: B12 1 mg/month IM, or 1-2 mg/day po
Folate deficiency: Improved diet, folate 1 mg/day

Monitor for a response to therapy.
Pernicious Anemia – monitor for gi cancers.

Question 7

Anemia of Chronic Disease

Answer 7

Microcytic anemia
Decreased serum Iron
Decreased serum TIBC
Normal Fe/TIBC percentage
Normal or increased ferritin

Question 8

Thalassemias

Answer 8

Genetic defect in hemoglobin synthesis
decrease synthesis of one of the 2 globin chains ( or )
Imbalance of globin chain synthesis leads to depression of hemoglobin production and precipitation of excess globin (toxic)
“Ineffective erythropoiesis”
Ranges in severity from asymptomatic to incompatible with life (hydrops fetalis)
Found in people of African, Asian, and Mediterranean heritage

Dx:
Smear: microcytic/hypochromic, misshapen RBCs
-thal will have an abnormal Hgb electrophoresis (HbA2, HbF)
The more severe -thal syndromes can have HbH inclusions in RBCs
Fe stores are usually elevated
Tx:
Mild: None
Severe: RBC transfusions + Fe chelation, Stem cell transplants

Question 9

Sideroblastic Anemias

Answer 9

Heterogenous grouping of anemias defined by presence of ringed sideroblasts in the BM
Etiologies:
Hereditary (rare), type of porphyria
Myelodysplasia
EtOH
Drugs (INH, Chloramphenicol)

Question 10

General Principles

Answer 10

Anemia is a sign, not a disease.
Anemias are a dynamic process.
Its never normal to be anemic.
The diagnosis of iron deficiency anemia mandates further work-up.