0071643192.pdf

HEMATOLOGY, ONCOLOGY, ALLERGY,

AND IMMUNOLOGY

TREATMENT

■ Treat underlying cause.

■ Provide PRBC transfusion as needed. Most sources recommend maintaining

hemoglobin above 10 g/dL in patients with evidence of cardiac ischemia.

Young, healthy patients may tolerate lower hemoglobin levels.

HEMOLYTIC ANEMIA

Hemolytic anemia results from the destruction of RBCs due to an inherited

oracquireddisorder (see Table 9.2). Destruction may occur within the blood

vessels (intravascular hemolysis) or as a result of sequestration elsewhere in

the body (extravascular hemolysis).

Signs and symptoms are generally attributed to the resultant anemia and in-

clude shortness of breath, fatigue, and pale or yellow skin. The spleen may be

enlarged, indicating splenic sequestration and destruction of RBC. Patients

with hemolysis may also present with symptomatic cholelithiasis or cholecysti-

tis as a result of bilirubingallstone formation.

A variety of tests are useful in the evaluation of the patient with suspected he-

molytic anemia (see Table 9.3).

Hereditary Spherocytosis

This autosomal dominant disease with a defect in red cell membrane protein

is common among persons of Northern European descent. Severity of hemo-

lysis ranges from mild to severe.

PATHOPHYSIOLOGY

■ RBCs take on a microspherocytic shape that is unable to pass through the

spleen→RBC destruction.

SYMPTOMS/EXAM

■ Anemia, jaundice, splenomegaly

■ Symptoms/findings consistent with cholelithiasis are common.

DIAGNOSIS

■ Peripheral smear with spherocytes

■ Negative Coombs test (to rule out autoimmune hemolytic anemia)

■ MCV may be decreased, indicating chronic hemolysis.

■ Osmotic fragility test is confirmative.

TABLE 9.2. Classification of Hemolytic Anemia

HEREDITARY ACQUIRED

Hereditary spherocytosis Immune-mediated

Thalassemia Microangiopathic

G6PD deficiency Infection (eg, malaria, babesiosis)

Sickle cell disease

Red cell production, measured

by a reticulocyte count, should

be increased in patients with

hemolytic anemia.