sickle cell disease Flashcards
EOR block 5
what population is most affected by SCD?
African American
what is SCD a result of ?
It is the result of a genetic mutation in the genes that encode for hemoglobin
what type of hemoglobin do patient with homozygous inheritance of the sickle cell inheritance have in their RBC?
They contain abnormal hemoglobin called hemoglobin S (HgbS or sickle hemoglobin)
what causes the abnormal “sickle” shape of RBC in SCD?
the presence of HgbS causes the RBCs to be rigid with a concave sickle shape.
What is the lifespan of sickled RBCs ?
Sickled RBCs undergo hemolysis after 10-20 days, which causes anemia
what is vascular occlusion?
The irregular shaped RBCs cannot transport oxygen effectively and they stick together blocking smaller blood vessels. Prevents oxygen from reaching the tissues causing them to become ischemic.
when do symptoms of SCD develop and why?
Sx develop approximately 2-3 months after birth. A fetus and young infants have RBCs with fetal hemoglobin (HgbF) which blocks the sickling of RBCs.
What can ischemia caused by vascular occlusion lead to in sickle cell disease?
Can lead to different types of sickle cell crisis:
1.Vaso-occlusive crisis VOC aka Acute pain crisis
what is acute chest syndrome
When there is pain in the chest and evidence of a pulmonary infection. This is life threatening and leading cause of death in SCD.
what are the most common chronic complications of SCD?
-Chronic pain *
others: avascular necrosis (bone death), pulmonary HTN, and renal impairment
what are acute SCD complications
- acute chest syndrome
- Anemia
- Cholecystitis (gallbladder infxn)
- infection
- Multiorgan failure (kidney, liver,lung)
- Priapism
- splenic sequestration
- stroke
- Vaso-occlusive crisis (acute pain crisis)
What are the chronic complications of SCD?
1.Avascular necrosis (bone death)
2. Depression and stress
3. Gallstones
4. Leg ulcers
5. Pain
6. Pregnancy complications (fetal death)
7. Pulmonary HTN
8. recurrent priapism
9. Renal impairment
10. Retinopathy
what are the functions of a healthy spleen ?
- Removal of old or damaged RBC
- immune function
- Clearing bacterial pathogens such as Streptococcus pneumoniae, H. Influenzae, and Neisseria meningitidis
what is the cause (1) and definition (2) of functional asplenia?
- The spleen becomes fibrotic and shrinks in size due to repetitive sickling and infarctions
- Decreased or absent spleen function, are at an increased risk of serious infection, require immunizations and ppx AB
what is the non drug txt for SCD?
- Blood transfusions
What is the goal Hgb in chronic monthly blood transfusions?
should be no higher than 10 g/dL post transfusion
what is one of the risk in blood transfusions?
Iron overload, which can lead to hemosiderosis (excess iron that impairs organ function). Chelation therapy to remove excess iron is used.
What is the only cure for SCD?
bone marrow transplantation but due to the high risk involved as well as the cost it not widely used
Which infections are particularly deadly in SCD and can lead to sepsis and meningitis?
Infections caused by Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis, and Salmonella species.
What helps reduce risk of death from invasive pneumococcal infection in young children with SCD?
ppx oral penicillin
What is the regimen for infants who screen positive for SCD a birth
They should be initiated on twice daily penicillin and treated until age five years.
what patients should receive penicillin ppx indefinitely?
1.If a patient undergoes surgical removal of the spleen
2.If invasive pneumococcal infection develops despite penicillin ppx
what are routine childhood series vaccines for patients with SCD?
- Haemophilus influenzae type b (Hib)
- Pneumococcal conjugate vaccine (PCV15- vaxneuvance or PCV20- prevnar 20)
what are additional vaccines for patients with functional asplenia?
- Meningococcal conjugate vaccine (MenACWY) series plus routine boosters (Menveo, MenQuadfi)
- Meningococcal serogroup B (Bexsero, Trumenba)*
- Pneumococcal vaccines- if never received as a child, give on of the following**
a. PCV20 x1 or
b. PCV15 x 1 followed by PPSV23 >8 weeks later
* age > 10 years
** age >19 years
