Sickle Cell Anemia

Sickle cell anemia is hereditary hemolytic anemia. This disease is characterized by presence of sickle and crescent shaped erythrocytes. The normal HbA that is adult hemoglobin is replaced by HbS that is abnormal sickle hemoglobin.

HbS defers from normal adult hemoglobin in the substitution of valine for glutamic acid in the sixth position of the beta chain. Presence of HbS imparts the sickle shape to deoxygenated red cells which is responsible for this disease. Under reduced oxygen tension, HbS molecules undergo crystallization within the red cell, which elongates and distorts the cells. The sickle cells themselves contribute to increased blood viscosity and circulatory stasis. The consequence is thrombosis which may lead to ischemia. 
Symptoms-
 1. Anemia.
 2. In majority of patients this disease remains asymptomatic. Manifestation of this disease may be acute or episodic and chronic or progressive.
  3. Severe abdominal pain and cramps. 
4. Bone and joint pain, haematuria, neurological manifestations or ulcers over the malleoli. 
5. In early stage splenomegaly occurs. But later on this spleen undergoes infarction and marked contraction with eventual autosplenectomy. 
6. Pain. 
7. Fever. 
8. Retarded growth. 
9. Development of bone and joint disease, pulmonary, hepatobiliary manifestation. 
10. Pigment gallstones appear later in life. 
11. Majority of patients with this disease die in the first decade of life, though a few may survive up to fifth decade. Death may result from intercurrent infections, cardiac or renal failure. 

Investigations- 
1. Blood smear- shows presence of characteristic sickle cells. 
2. Hemoglobin electrophoresis- shows predominately HbS and variable amounts of HbF and no HbA. 
3. Leucocytosis. 
4. Increased number of platelets. 
5. Elevation of serum bilirubin.
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