Sickle Cell

Question 1

what is sickle cell dz

Answer 1

• inherited autosomal recessive disorder

- Defect in hemoglobin molecule , specifically a variant in beta globin polypeptide

Question 2

HbF

Answer 2

fetal hemoglobin, replaced by HbA (adult hemoglobin) during postnatal period

Question 3

HbS

Answer 3

sickle hemoglobin, inherited variant of HbA

Question 4

Hemoglobin S

Answer 4

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

Question 5

Sickle cell trait

Answer 5

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

Question 6

Sickle cell dz (SS)

Answer 6

• 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)

Question 7

Hemoglobin sickle C dz (SC)

Answer 7

HbS and HbC, moderate to severe hemolytic anemia, increased risk for splenomegaly, retinal dz, and aseptic necrosis

Question 8

Sickle/Beta Thalassemia (SA)

Answer 8

HbS and beta thalassemia, manifestations depend on degree of thalassemia

Similar to homozygous SS dz but have milder symptoms and crises

Question 9

Hallmark of sickle cell

Answer 9

vaso-occlusive phenomena and hemolytic anemia

Question 10

Sickle cell crisis

Answer 10

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

Question 11

What 2 hematology dzs are protective against malaria

Answer 11

Thalassemia and sickle cell trait are protective against plasmodium falciparum malaria

Question 12

neuro complications with sickle cell

Answer 12

TIA, stroke, unexplained coma, epilepsy, neurocognitive decline

Question 13

Leading cause for morbidity and mortality for sickle cell

Answer 13

• infection due to splenic dysfunction
• bacterial infections: step pneumoniae and haemophilus influenzae
• viral infections: H1N1, parovirus

Question 14

Sickle cell symptoms related to vaso-occlusion

Answer 14

generalized pain in long bones and joints, fever, fatigue, malaise, abdomen pain, nausea, vomiting, decreased appetitie, swelling in hands and feet and joints, priapism

Question 15

sickle cell symptoms unrelated to vaso-occlusion

Answer 15

depression, chronic hemolytic anemia, tachycardia, fever, tachypnea, splenomegaly (frequent in (SC), hepatomegaly, jaundice, cardiomegaly, retinopathy, physical immaturity, leg ulcers from trauma

Question 16

test to confirm sickle cell

Answer 16

• hemoglobin electrophoresis

- Will confirm hemoglobin genotype for sickle cell dz, and hemoglobin F (fetal) and A2 for presence of thalassemia

Question 17

Hematocrit in sickle cell

Answer 17

low, usually 20-30

Question 18

retic count in sickle cell

Answer 18

markedly elevated, 10-25%

Question 19

WBC count in sickle cell

Answer 19

elevated 12,000-15,000

Question 20

peripheral blood smear sickle cell

Answer 20

5-50% of cells are sickled

Question 21

Positive diagnosis of sickle cell, hemoglobin S: Hemoglobin S,A, and F

Answer 21

-Hemoglobin S: constitutes 85-95% of hemoglobin
-Hemoglobin A: not present in homozygous S dz
-Hemoglobin F are increased (associated with more benign dz)
)

Question 22

What lab levels are elevated with sickle cell (8)

Answer 22

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

Question 23

what labs are decreased in sickle cell (3)

Answer 23

Serum creatinine (b/c of increased GFR of kidneys, except in renal failure. Expect protein in urine
Plasma protein C
Plasma Protein S

Question 24

Imaging for sickle cell dz

Answer 24

Transcranial Doppler US to identify risk for stroke

CT and MRI to rule out aseptic necrosis

Question 25

Pain management in sickle cell

Answer 25

- 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

Question 26

O2 use in sickle cell crisis

Answer 26

give to hypoxic patients with partial pressure <60-70 mmHg, use humidified 02 at 40%

Question 27

Other meds for sickle cell crisis besides opiates

Answer 27

NSAIDS Antihistamines Tricyclic antidepressants Phenothiazines for nausea and vomiting

Question 28

When to give transfusion

Answer 28

``` Symptomatic anemia acute events preop for major surgery acute sepsis or meningitis Prevention of recurrent stroke Chronic hypoxia recurrent and chronic anemia ```

Question 29

Prevention measures and chronic dz management

Answer 29

- 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

Question 30

Birth control with sickle cell

Answer 30

NOT contraindicated | consider genetic counseling

Question 31

Sickle cell cure

Answer 31

- in children | - with hematopoietic cell transplantaion

Question 32

Home meds that may help pain crisis

Answer 32

hydroxyurea and aliphatic butyrate salts decrease pain crisis by increasing level of fetal hemoglobin

Question 33

When is onset of sickle cell?

Answer 33

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

Question 34

Acute chest syndrome

Answer 34

acute chest pain , hypoxemia, pulmonary infiltrates on CXR

Question 35

Complications of sickle cell

Answer 35

-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

Question 36

Presentation of sickle cell pt

Answer 36

``` chronically ill jaundiced hepatomegaly enlarged heart with systolic murmurs and hyperdynamic precordium Nonhealing ulcers retinopathy ```

Question 37

average life expectancy and cause of death for sickle cell

Answer 37

40-50 years old | death caused by multisystem organ failure