Sickle Cell Flashcards
When does HbS polymerize? In the oxygenated or deoxygenated state?
In the deoxygenated state
What is the primary cause of HbS polymerization? What other factors increase the likelihood of polymerization?
Deoxygenated state; fever, acidosis, dehydration
When is sickle cell disease diagnosed? What is given following diagnosis?
As a newborn- give antibiotics prophylactically because of the risk of sepsis
What is sickle cell trait (AS)?
Heterozygous for disease; asymptomatic
What is homozygous sickle cell anemia (SS)?
Homozygous for disease; most severe
What is HbSC disease?
One parent is AS and the other is AC;HbC doesn’t usually sickle but increases the viscosity of HbS; milder
What is sickle beta thalassemia?
One parent is AS and the other is alpha thalassemia (doesn’t produce any beta chains); severity depends on if thalassemia produces no HbA
What is a major cause of death in kids with sickle cell disease?
Bacterial sepsis
Sickle cell patients are immunocompromised because of vaso-occlusion to spleen. What is a complication of their inability to mount an immune response?
Purpura fulminas- skin necrosis that may result in amputation because circulation is so poor
What is the first vaso-occlusive episode seen in sickle-cell patients as infants? How does it change over time? How should they be treated?
First: hand-foot syndrome (swelling of hands and feet)
Over time these episodes spread throughout the body
Treat with narcotics
How can stroke occur in children with sickle cell disease?
Vaso-occlusion of arterial vessels to the brain
What is the treatment for children with sickle cell who have a stroke? How can it be prevented?
Treatment: RBC transfusions and maybe BM transplant
Prevention: transcranial doppler
What is acute chest syndrome?
Unique to sickle cell disease; diffuse and bi-lateral loss of space in lungs with an unknown cause
What is the most common cause of death for sickle cell patients over the age of 5?
Acute chest syndrome
How is acute chest syndrome treated?
Antibiotics, oxygenation, incentive spirometry
What is acute splenic sequesteration crisis?
Sudden enlargement of the spleen due to acute vaso-occlusion in sickle cell patients
What is the potentially life threatening effect of splenic sequesteration crisis? How is it treated?
Hypovolemic shock; fluids and transfusion
What is currently the only cure for sickle cell disease?
BM transplant
What is the correlation between the number of crises/ year and the severity of disease?
Greater than 3= severe
1-3= moderate
1= mild
Where does erythropoeisis begin? How does it transition as the fetus develops? What are the different structures seen for the beta chain?
Begins in yolk sac (epsilon chains)–> liver (gamma)–> at birth to BM (beta)
What gene is located on chromosome 6 and how is it related to the transition from HbF to HbA?
MYB- results in decreased gamma synthesis
What gene is located on chromosome 2 and how is it related to the transition from HbF to HbA?
BCL- transcriptional repressor and gamma globin silencer
Generally, variants of sickle cell disease that have more HbF are more or less severe?
Less severe
The polymerization of HbS leads to vaso-occlusion and ischemia. What is enzyme is increased in response? How does this lead to a cyclic effect?
Xanthine oxidase; when oxygen returns the xanthine oxidase released free radicals leading to NFkB activation, which leads to inflammation the release of cytokines and activation of WBC which then bind to RBC and occlude a vessel
