Sicke Cell Disease Flashcards
Sickle cell disease is an autosmal __________ disease in which there is chronic hemolytic anemia and vasoocclusion
Recessive
There is _________{extravascular/intravascular} hemolysis in SCD
Extravascular hemolysis
Sickle cell disease is caused by a missense _________ mutation with substitution of valine for glutamic acid at the ________ position of the B globin chain
Point mutation
Sixth
Heterozygous people have _______ (no/little/mild) anemia
No
Homozygous condition HbSS produces a severe __________(microcytic/normocytic/macrocytic) anemia
Normocytic
Sickle cells are protective against _____________
Plasmodium falciparum malaria
Most life threatning complications of sickle cell diseases?
Acute chest syndrome
Stroke
Infection
HbS molecules in the RBCs aggregate and polymerize into long, needle like fibers when __________ (deoxygenated/oxygenated)
deoxygenated
Oxygen ________ (favours/inhibits) sickling of RBCs
inhibits
HbS concentration should be more than ____% for sickling to occur
60%
In sickle cell trait, HbS concentration is less than ____% so sickling doesn’t occur
50%
What are the factors that increase the concentration of deoxyhemoglobin?
Acidosis
Volume depletion
Hypoxemia
What are the factors that increase the concentration of deoxyhemoglobin?
Acidosis
Volume depletion
Hypoxemia
Acidosis shift the O2 dissociation curve to the ______ (right/left) causing O2 release from RBCs and leading to increase in deoxyHb
right
How does volume depletion causes sickling?
Volume depletion in which intracellular dehydration causes an increase in concentration of deoxyHb
Initial sickling is _________ (reversible/irreversible)
reversible (if O2 is administered)
_________ sickling is irreversible because of membrane damage
Recurrent
How membrane damage makes sickling an irreversible thing?
An influx of calcium ions cross links membrane proteins, causing the eflux of K+ and water out of the cell and cell gets dehydrated
Sickle cells undergo hemolysis in the liver, spleen so it is __________ (extrvascular/intravascular) hemolysis
extravascular
How does vasoocclusion occur in SCD?
Sickle cells are sticky bcz of increased expression of adhesion molecules on their surface leading to ischemic injury
What is the mechanism of hydroxyurea?
Hydroxyurea stimulates the synthesis of HbF, HbF has high affinity for O2 so no sickling
Increased HbF at birth prevents sickling until ______ months of age
5-6 months
What are the clinical findings in SCD?
15 findings
Severe anemia Vasoocclusive crisis Dactylitis Acute chest syndrome Avascular necrosis of bone Autosplenectomy Increased susceptibility to infections Aplastic RBC crisis Sequestration crisis Calcium and bilirubinate gallstones Acute n chronic liver disease Stroke Recurrent leg ulcers Proliferative retinopathy Endstage renal failure
frequency of VOC is variable but may be as many as ____ or more crises a year
six
