9 - Sickle Cell Disease

Question 1

which form of Hb is more likely to sickle - oxy or deoxy?

Answer 1

deoxy

Question 2

two main causes of complications of sickle cell disease

Answer 2

hemolysis

viscosity

Question 3

hemolysis related complications of SCD

Answer 3

stroke, pulm HTN, priapism, leg ulcers

Question 4

viscosity related complications of SCD

Answer 4

avascular necrosis, proliferative retinopathy, pain crisis, acute chest syndrome

Question 5

best predictor of clinical severity in SCD

Answer 5

HbF levels

Question 6

how do higher HbF levels improve outcomes in SCD?

Answer 6

first off, less cells that CAN sickle

also, HbF inhibits sickling of HbS

Question 7

how does co-inheritance of alpha thalassemia affect the clinical course of SCD?

Answer 7

less Hb in cell > lower Hb conc > less sickling

fewer hemolytic complications, but higher viscosity related complications

Question 8

PBS findings in SC anemia

Answer 8

sickling (duh)
Howell Jolly bodies (result of functional asplenia)
lots of retics

Question 9

early clinical problems in SC anemia

Answer 9

splenic infarction > functional asplenia by 3-6 yrs
dactylitis
pain episodes
stroke

Question 10

what type of strokes do SC anemia pts tend to have?

Answer 10

children - ischemic

adults - hemorrhagic

Question 11

main strategy for stroke prevent in SCD

Answer 11

chronic transfusions

Question 12

way to determine stroke risk in SCD patients

Answer 12

transcranial doppler ultrasound

high risk when velocity > 200 cm/s

Question 13

acute chest syndrome

Answer 13

may develop day 3-4 of pain crisis

pain, dyspnea, fever, pulm infiltrates, leukocytosis

Question 14

tx of acute chest syndrome

Answer 14

abx, incentive spirometry, O2, transfusion/exchange

Question 15

high tricuspid regurgitant velocity in a sickle cell patient suggests

Answer 15

pulmonary hypertension, associated with early mortality

Question 16

causes of death in SCD pts

Answer 16

organ failure - renal, hepatic, pulm htn

acute events - acute chest, stroke, sepsis (2/2 asplenia)

Question 17

preventative care for SCD

Answer 17

vaccines for encapsulated orgs
prophylactic PCN until 5 yo

check UA for protein, ophtho for prolif retinopathy, echocardiogram?

Question 18

hydroxyurea - what does it do

Answer 18

inc HbF production > less sickling

may also dec endothelial adhesion and WBC

Question 19

side effects / warnings for hydroxyurea

Answer 19

birth defects (not observed, just evidence in animals)
risk for hematologic malignancy? no evidence

GI sx
skin hyperpigmentation
excessive myelosuppression

Question 20

clinical manifestations of sickle trait

Answer 20

splenic infarction at high altitude
asymptomatic bacteriuria in women
low urine specific grav
hematuria
pulm embolism
glaucoma 2/2 hyphema
sudden death during exercise
renal medullary CA

bottom line: urine/kidney stuff and sudden death

Question 21

Hemoglobin SC dz

Answer 21

C dehydrates cell - get “fat sickles”, lots of targeting, and spherocytes
get viscosity related complications, but overall milder course
spleen function lasts longer - early adulthood

Question 22

how does the course of HbSbeta-thalassemia compare to other SCD types?

Answer 22

similar to HbSS