CHAPTER 4 Hematologic System^197
Sickle Cell Anemia
WHAT WENT WRONG?
This is an autosomal recessive disorder in which an abnormal gene causes damage
to the RBC membrane. The abnormal hemoglobin within the red blood cell is called
hemoglobin S. Dehydration or drying of the RBC makes it more vulnerable to sick-
ling (forming a crescent-like shape), as do hypoxemia and acidosis. Hemolytic ane-
mia results as RBCs are destroyed due to the damage to the outer membrane. The
sickled cells can also clump together, causing difficulty getting through the smaller
vessels.
PROGNOSIS
Sickle cell anemia will become a chronic multisystem disease. Causes of death in
these patients are usually related to organ failure. Patients may also inherit a single
gene for sickle cell. These patients may develop sickle cell trait, in which symp-
toms would only be present in the setting of extreme circumstances (vigorous
exercise at high altitude, especially with rapid ascent).
HALLMARK SIGNS AND SYMPTOMS
- Acute pain (especially back, chest, and long bones) from vascular occlusion
of the small vessels as the sickled cells clump - Fever as body responds to acute sickling episode and accompanying pro-
voking event - Painful, swollen joints due to vaso-occlusive process
- Fatigue due to chronic anemia
- Stroke (cerebrovascular accident) due to vaso-occlusive process
- Enlarged liver (hepatomegaly)
- Enlarged heart and systolic murmur
INTERPRETING TEST RESULTS
- Low RBC count due to chronic hemolytic anemia; the RBCs have a shorter
lifespan.
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