Sickle Cell Flashcards
what is sickle cell dz
- inherited autosomal recessive disorder
- Defect in hemoglobin molecule , specifically a variant in beta globin polypeptide
HbF
fetal hemoglobin, replaced by HbA (adult hemoglobin) during postnatal period
HbS
sickle hemoglobin, inherited variant of HbA
Hemoglobin S
variants of beta globin gene (HbS)
-dz expression occurs with inheritance of 2 copies of HbS, or HbS and another copy of beta globin variant
Sickle cell trait
when someone has sickle cell trait, they have HbS and HbA, no expression of disease. Under extreme circumstances pt can have mild expression of dz
May get renal dz, hematuria
Sickle cell dz (SS)
- pt will have HbS and Hbs, moderate to severe hemolytic anemia in first months of life.
- uncompensated hemolytic anemia, shortened RBC survival (16 days vs 120 days normally), increased RBC production (Erythropoiesis)
Hemoglobin sickle C dz (SC)
HbS and HbC, moderate to severe hemolytic anemia, increased risk for splenomegaly, retinal dz, and aseptic necrosis
Sickle/Beta Thalassemia (SA)
HbS and beta thalassemia, manifestations depend on degree of thalassemia
Similar to homozygous SS dz but have milder symptoms and crises
Hallmark of sickle cell
vaso-occlusive phenomena and hemolytic anemia
Sickle cell crisis
vaso occlusive leading to tissue ischemia and acute pain, acute chest syndrome, sequestration crisis, aplastic crisis, increased risk for stroke, organ damage, bacterial infection, and complications from blood transfusions
What 2 hematology dzs are protective against malaria
Thalassemia and sickle cell trait are protective against plasmodium falciparum malaria
neuro complications with sickle cell
TIA, stroke, unexplained coma, epilepsy, neurocognitive decline
Leading cause for morbidity and mortality for sickle cell
- infection due to splenic dysfunction
- bacterial infections: step pneumoniae and haemophilus influenzae
- viral infections: H1N1, parovirus
Sickle cell symptoms related to vaso-occlusion
generalized pain in long bones and joints, fever, fatigue, malaise, abdomen pain, nausea, vomiting, decreased appetitie, swelling in hands and feet and joints, priapism
sickle cell symptoms unrelated to vaso-occlusion
depression, chronic hemolytic anemia, tachycardia, fever, tachypnea, splenomegaly (frequent in (SC), hepatomegaly, jaundice, cardiomegaly, retinopathy, physical immaturity, leg ulcers from trauma
test to confirm sickle cell
- hemoglobin electrophoresis
- Will confirm hemoglobin genotype for sickle cell dz, and hemoglobin F (fetal) and A2 for presence of thalassemia
Hematocrit in sickle cell
low, usually 20-30
retic count in sickle cell
markedly elevated, 10-25%
WBC count in sickle cell
elevated 12,000-15,000
peripheral blood smear sickle cell
5-50% of cells are sickled
Positive diagnosis of sickle cell, hemoglobin S: Hemoglobin S,A, and F
-Hemoglobin S: constitutes 85-95% of hemoglobin
-Hemoglobin A: not present in homozygous S dz
-Hemoglobin F are increased (associated with more benign dz)
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What lab levels are elevated with sickle cell (8)
Serum indirect bilirubin (levels high) Serum transaminase Alkaline phosphatase Factor VIII activity von Willebrand factor antigen Thrombin Platelets (thrombocytosis) Howell Jolly bodies and target cells with hyposplenism
what labs are decreased in sickle cell (3)
Serum creatinine (b/c of increased GFR of kidneys, except in renal failure. Expect protein in urine
Plasma protein C
Plasma Protein S
Imaging for sickle cell dz
Transcranial Doppler US to identify risk for stroke
CT and MRI to rule out aseptic necrosis
Pain management in sickle cell
- prompt tx
- morphine, dilaudid
- hospitalize if pain does not improve
- oral opiods for breakthrough pain
- NS boluses (0.5-1L)to reduce viscosity but avoid overload
- Maintenance fluids: 1/4 or 1/2 NS and encourage oral intake
O2 use in sickle cell crisis
give to hypoxic patients with partial pressure <60-70 mmHg, use humidified 02 at 40%
Other meds for sickle cell crisis besides opiates
NSAIDS
Antihistamines
Tricyclic antidepressants
Phenothiazines for nausea and vomiting
When to give transfusion
Symptomatic anemia acute events preop for major surgery acute sepsis or meningitis Prevention of recurrent stroke Chronic hypoxia recurrent and chronic anemia
Prevention measures and chronic dz management
- Folic acid daily
- long term transfusion to prevent stroke if US positive
- Pneumo, hepatitis, and flu vaccines
- Foot care and protective shoes
- annual PCP visit and 2-3 per year after age 30
- annual eye exam until adult then every 2-3 years
- chelation therapy with Deferoxamine if in iron overload
- routine exchange transfusions
- Ace inhibitors for microalbuminuria
- Avoid temp extremes and physical exertion
Birth control with sickle cell
NOT contraindicated
consider genetic counseling
Sickle cell cure
- in children
- with hematopoietic cell transplantaion
Home meds that may help pain crisis
hydroxyurea and aliphatic butyrate salts decrease pain crisis by increasing level of fetal hemoglobin
When is onset of sickle cell?
during 1st year of life, when hemoglobin F levels fall as a signal is sent to switch from production of gamma globin to beta globin
Acute chest syndrome
acute chest pain , hypoxemia, pulmonary infiltrates on CXR
Complications of sickle cell
-Osteomyelitis from ischemic necrosis of bone
-Infarction of renal medulla causing hematuria (happens more with sickle cell trait
-Retinopathy
-Pulmonary HTN
Delayed puberty
More prone to infection because of hyposplenism
Presentation of sickle cell pt
chronically ill jaundiced hepatomegaly enlarged heart with systolic murmurs and hyperdynamic precordium Nonhealing ulcers retinopathy
average life expectancy and cause of death for sickle cell
40-50 years old
death caused by multisystem organ failure
