Sick Cell Anemia Flashcards
(15 cards)
What genetic mutation causes sickle cell disease?
A point mutation in the β-globin gene (Glu6Val) replaces glutamic acid with valine, producing Hemoglobin S (HbS).
How does Hemoglobin S (HbS) lead to sickle-shaped red blood cells?
HbS polymerizes under low oxygen, dehydration, or stress, making RBCs rigid and sickle-shaped.
Why do sickled red blood cells cause pain crises?
Sickled cells occlude small blood vessels, causing ischemia and intense pain (vaso-occlusive crises).
What are the main triggers for sickle cell crises?
Infection, dehydration, hypoxia, cold exposure, and stress (including pregnancy).
What is the inheritance pattern of sickle cell disease?
Autosomal recessive.
What are the hallmark lab findings in sickle cell anemia?
Low hemoglobin, high reticulocytes, sickle cells on smear, high LDH, high unconjugated bilirubin, low haptoglobin.
What is the definitive diagnostic test for sickle cell disease?
Hemoglobin electrophoresis showing HbS and no or low HbA.
What are the complications of hyposplenism in sickle cell disease?
Increased risk of infections, especially from encapsulated organisms (e.g., S. pneumoniae).
What are the features of acute chest syndrome?
Fever, chest pain, tachypnea, hypoxia, and pulmonary infiltrates.
How does repeated transfusion lead to iron overload?
Excess iron accumulates in organs like the heart and liver, leading to complications like cardiomyopathy.
What are common thrombotic complications in sickle cell disease?
Stroke and pulmonary embolism.
What musculoskeletal complication is common in SCD?
Avascular necrosis, especially of the femoral head.
What are the maternal risks during pregnancy with SCD?
Increased frequency of crises, infections, pre-eclampsia, and cesarean delivery.
What are fetal risks in pregnancies complicated by SCD?
Miscarriage, IUGR, prematurity, stillbirth, and increased perinatal mortality (4–6×).
What is the role of hydroxyurea in sickle cell disease?
It increases fetal hemoglobin (HbF), which reduces sickling and frequency of crises.
