0071643192.pdf

HEMATOLOGY, ONCOLOGY, ALLERGY,

AND IMMUNOLOGY

TREATMENT

■ Folic acid, splenectomy

Thalassemia

This genetic disorder is characterized by underproduction of either alphaor
betaglobin chains of the hemoglobin molecule. Thalassemia occurs in peo-
ple of Mediterranean, African, Middle Eastern, Indian, and Asian descent.

ALPHATHALASSEMIA

Occurs when one or more of the four alpha globin chain genes fails to func-
tion. Severity of disease depends on number of genes deleted or mutated.

■ Carrier state:One deletion
■ No anemia, asymptomatic
■ CBC: No abnormalities on CBC
■ Alpha thalassemia minor: Two deletions
■ Usually asymptomatic
■ CBC: Mild microcytic anemia
■ Hemoglobin H disease: Three deletions
■ Splenomegaly, jaundice, chronic microcytic anemia
■ Avoid oxidative drugs (same drugs to be avoided with G6PD deficiency);
see Table 9.3.
■ Hydrops fetalis:Four deletions
■ Fetal demise, total body edema

TABLE 9.3. Tests Used in the Evaluation of Hemolytic Anemia

CBC Anemia (normocytic if acute)

Peripheral smear

Spherocytes RBC membrane destruction, seen in autoimmune hemolytic

anemia and hereditary spherocytosis

Schistocytes RBC fragmentation, seen in microangiopathic hemolytic anemia

Heinz bodies RBCs with precipitated hemoglobin, indicating G6PD deficiency

Reticulocytes Should be elevated in hemolysis

Haptoglobin Binds to free hemoglobin, therefore decreased in hemolysis

Lactate dehydrogenase Elevated in hemolysis

Indirect bilirubin Elevated indirect (unconjugated) bilirubin in hemolysis

Direct Coomb test Positive if IgG or complement present on RBC surface

Osmotic fragility test Positive in hereditary spherocytosis

Patients with severe forms of

thalassemia are at risk of

heart failure due to anemia

and iron toxicity resulting from

numerous blood transfusions.