Sickle Cell Anemia

Question 1

Define sickle cell anemia

Answer 1

Autosomal Recessive, Hereditary Haemoglobin disorder

Question 2

Mutation in sickle cell anemia occurs where

Answer 2

in beta globin gene, leading to substitution of Valine for Glutamic Acid

Question 3

Sickling will lead to?

Answer 3

• Increased destruction of red cells
• Aggregation of distorted cells in blood circulation leading to ischemic tissue damage

Question 4

Deoxygenationof mutant Hb leads to

Answer 4

• increased K+efflux
• Increased cell density / dehydration
• increased polymerization

Question 5

Explain with short words the pathophysiology of Sickle cell anemia

Answer 5

• Deoxygenation of mutant Hb
- increased K+efflux
- Increased cell density / dehydration
- increased polymerization
• Sickled cells adhere to endothelial cells
• Endothelial factors increases vasoconstriction
• low Blood flow promotes vaso-occlusion
• “Vicious cycle” with decreased blood flow, hypoxemia / acidosis, increased sickling
• Some cells become irreversibly sickled

Question 6

Factors That increases HbS polymerzation

Answer 6

• Decreased oxygen
• Increased intracellular hemoglobin S concentration
• Increased 2,3-DPG
• Decreased pH
• Slowed transit time through the circulation
• Endothelial adhesion

Question 7

Factors That decreases HbS polymerzation

Answer 7

• Lower concentration of HbS
• Increased HbF levels
– Genetic basis
– Hydroxyurea

Question 8

Clinical Features of Sickle Cell Anemia
Name as much as you can

Answer 8

• Painful episodes
• Pneumococcal disease
• Acute chest syndrome
• Splenic infarction
• Splenic sequestration
• Stroke Stroke
• Osteonecrosis
• Priapism
• Retinopathy
• Leg ulcers
• Gallstones
• Renal abnormalities
• Osteopenia
• Nutritional deficiencies
• Placental insufficiency
• Pulmonary hypertension

Question 9

Features of Sickle cell anemia

Answer 9

• First shift (from HbF to HbS) typified by acute problems: high risks of severe life-threatening infection, acute chest syndrome, splenic sequestration, and stroke
• Chronic organ damage renal failure, pulmonary
  hypertension, and late effects of previous
  cerebrovascular disease) becomes paramount in
  adults.

Question 10

The formation of HbS has two major consequences, what are they?

Answer 10

(i) A chronic Haemolytic Anameia
(ii) Occlusion of small blood vessels, resulting in ischemic tissue damage

Question 11

Variability in sickling depends on how many factor? Name them please?

Answer 11

1- Concentration of HbS
2-Cellular Dehydration
3. Other Haemoglobins
4-Deoxygenation
5-Caliber of blood vessels
6-Duration of Hypoxia
7-Cold Weather
8- Acidosis

Question 12

Crises are often precipitated by?

Answer 12

a-Infections
b-Dehydration due to fever and gastrointestinal loss of fluid
c-Acidosis
d-Hypoxia from Pneumonia.

Question 13

Difference of Clinical features of sickle cell anemia asssociated with higher HB and with Lower HB

Answer 13

Higher: Painful episodes, Acute chest syndrome, Osteonecrosis, Proliferative retinopathy
Lower: Stroke, Priapism, Leg Ulcers

Question 14

Clinical manifestation of SCA?

Answer 14

In infancy anemia and jaundice
hand and foot Syndrome
splenic sequestration and fulminent Pneumonia
Auto splenectomy
Normal growth and delopment but there may be some skeletal deformities, including frontal bossing of the skull due to expansion of bone marrow.

Question 15

If a patient has a palpable spleen after the first decade then probably he is suffering from?

Answer 15

Sickle Cell – Beta Thalassaemia Disease

Question 16

List all acute complications of Sickle Cell Anaemia

Answer 16

1. Painful Vaso- occlusive crisis
2. Aplastic Crises
3. Splenic and Hepatic Sequestration Crises
4. Acute Chest Syndrome
   5.CNS Crises
5. Hyperhemolytic Crises
6. Megaloblastic Crises

Question 17

List all chronic complications of Sickle Cell Anaemia

Answer 17

1. Severe Infections (Pneumococcal Septicemia, Salmonella Osteomyelitis)
2. Infarcts following repeated episodes of vascular occlusion (Bone Infarcts, Renal infarcts)
3. Priapism
4. Chronic, relapsing leg ulcers
5. Occular manifestations

Question 18

Sickle Cell Anemia treatment

Answer 18

• Hydration for painful crises
• Pneumococcal vaccination
• Retinal surveillance
• Transfusion for serious manifestations
• Hydroxyurea
• Stem cell transplant

Question 19

Labratory diagnosis for SCA

Answer 19

• Haemoglobin level
• Sickle cells on peripheral blood (should be less than 30%)
• Reticulocyte Count (elevated)
• Haemoglobin Electrophoresis
• Bilirubin level
• Serum LDH
• Blood Gases
• Renal Function Tests
• Prenatal Diagnosis

Question 20

Sickle trait Definition screening tests symptoms and prevention

Answer 20

• benign condition with no anaemia and normal
appearance of red cells on a blood film
• Screening Tests for Sickle cell are positive
• Haemoglobin electrophoresis will show 25 – 45% HbS, rest is HbA.
• Haematuria is the most common symptom and is
thought to be caused by infarcts of renal papillae
• Care must be taken with anaesthesia, pregnancy, at
high altitudes and during strenuous exercises.