Sickle Cell Anemia

2 min read

INTRODUCTION

Sickle cell anemia is an inherited red blood cell disorder caused by a point mutation in the beta globin gene that results in the production of abnormal hemoglobin S. It is inherited in an autosomal recessive pattern.

Test Catageory
فئة التحليل

Hematology

Refrence Books
كتب مراجع

1. Daice & Lewis Practical Hematology

Skills Required
المهارات المطلوبة

1. Microscopy
2. Good Interpretation

Video Resources
مصادر فيديو

عربي
English

Etiology (Causes)

Sickle cell anemia is caused by a single nucleotide substitution in the beta globin gene. This leads to replacement of glutamic acid with valine at position 6 of the beta globin protein. This single amino acid change causes hemoglobin S to form rigid polymers when deoxygenated, distorting red blood cells into the characteristic sickle shape.

Pathophysiology

The mutant hemoglobin S polymerizes when deoxygenated, causing the red cells to become rigid and sickle-shaped. These sickled cells obstruct blood vessels and cause both chronic hemolytic anemia and recurrent painful vaso-occlusive crises.

Sample Type

1. Peripheral blood collected in EDTA for complete blood count and peripheral smear (PBP)

Tests Required to Diagnose Sickle Cell Anemia

Complete Blood Count:
1. Perform automated CBC – check for anemia, thrombocytosis, leukocytosis
2. Prepare peripheral smear and stain with Wright stain
3. Examine under microscope for sickle cells, target cells
Hemoglobin Electrophoresis:
1. Use cellulose acetate electrophoresis at alkaline pH
2. Lyse RBCs to release hemoglobin types
3. Separate hemoglobin types based on electrophoretic mobility
4. Stain and visually inspect bands

Result Interpretation

1. Normocytic, Normochromic RBCs with Sickle Cells and Nucleated RBCs on smear
2. Normal MCV, MCH, MCHC in CBC
3. in Electrophoresis Sickle cell anemia shows:
– Hb S band >80%
– Hb A band <20%
– Sickle cell trait shows both Hb A and Hb S bands approximately equal
4. Solubility Test is Positive
5. Sickling Test is Positive
6. TWBCs Count Must Be Corrected if nRBCs Are Present