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Haematology > Sickle Cell Disease > Flashcards

Sickle Cell Disease Flashcards

1
Q

Define Sickle Cell Disease?

A

A chronic condition with sickling of red blood cells caused by inheritance of haemoglobin S (HbS)

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2
Q

What is Sickle Cell Anaemia?

A

Homozygous HbS

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3
Q

What is Sickle Cell Trait?

A

Carrier of one copy of HbS

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4
Q

What is Sickle Cell Disease?

A

Includes compound heterozygosity for HbS and:
HbC (abnormal haemoglobin in which glutamic acid is replaced by lysine at the 6th position in the beta-globin chain)
Beta-thalassemia

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5
Q

What is the aetiology of Sickle Cell Disease?

A

Autosomal recessive
Caused by a point mutation in the beta-globin gene resulting in the substitution of glutamic acid in position 6 by valine
This results in the formation of abnormal haemoglobin S
Deoxygenation of HbS alter the conformation resulting in sickling of red cells
Sickling makes the red cells more fragile and inflexible

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6
Q

What are the sickled red cells prone to?

A

Sequestration and destruction (reduced red cell survival ~ 20 days)
Occlusion of small bowel vessels causing hypoxia, which leads to further sickling and occlusion

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7
Q

What are the factors that precipiate sickling in Sickle Cell Disease?

A

Infection
Dehydration
Hypoxia
Acidosis

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8
Q

What is the epidemiology of Sickle Cell Disease?

A

Rarely present before 4-6 months (because HbF can compensate for the defect in adult haemoglobin)
Common in Africa, Caribbean, Middle-East and other areas with a high prevalence of malaria

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9
Q

What are the presenting symptoms of Sickle Cell Disease?

A

Symptoms secondary to VASO-OCCLUSION or INFARCTION

Symptoms of SEQUESTRATION CRISIS

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10
Q

What are the symptoms secondary to VASO-OCCLUSION of INFARCTION related to Sickle Cell Disease?

A 
Autosplenectomy (splenic atrophy or infarction)
Abdominal Pain 
Bones 
Myalgia and Arthralgia 
CNS 
Retina
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11
Q

What does Autosplenectomy lead to in Sickle Cell Disease?

A

Increased risk of infections with encapsulated organisms (e.g. pneumococcus, meningococcus)

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12
Q

What symptoms happen to the bones in Sickle Cell Disease?

A

Painful crises affect small bones of the hands and feet causing dactylitis in CHILDREN
Painful crises mainly affect the ribs, spine, pelvis and long bones in ADULTS

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13
Q

What CNS symptoms can occur in Sickle Cell Disease?

A

Fits and Strokes

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14
Q

What happens to the Retina in the Sickle Cell Disease?

A

Visual loss (proliferative retinopathy)

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15
Q

When does a Sequestration Crisis happen in Sickle Cell Disease?

A

Occurs due to pooling of red cells in various organs (mainly the spleen)

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16
Q

What is the Hepatic Symptom as a result of a Sequestration Crisis in Sickle Cell Disease?

A

Exacerbation of Anaemia

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17
Q

What are the symptoms related to the lungs as a result of a Sequestration Crisis in Sickle Cell Disease?

A

Acute Chest Syndrome
Cough
Pain
Fever

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18
Q

What is the other main symptom of Sequestration Crisis in Sickle Cell Disease?

A

Persistent Painful Erection (priapism)

Impotence

19
Q

What are the signs of Sickle Cell Disease on physical examination?

A

Signs secondary to Vaso-Occlusion, Ischaemia or Infarction
Retina signs
Signs secondary to Sequestration Crisis
Signs of Anaemia

20
Q

What are the signs secondary to VASO-OCCLUSION, ISCHAEMIA or INFARCTION in Sickle Cell Disease?

A

Bone - joint or muscle tenderness or swelling (due to avascular necrosis)
Short digits - due to infarction in small bone of the hands

21
Q

What are the signs on the Retina for Sickle Cell Disease?

A

Cotton wool spots due to retinal ischaemia

22
Q

What are hre Signs secondary to sequestration crisis in Sickle Cell Disease?

A

Organomegaly

Priaprism

23
Q

What is Organomegaly in Sickle Cell Disease?

A

The spleen is enlarged in early disease

Later on, the spleen will reduce in size due to splenic atrophy

24
Q

What investigations for Sickle Cell Disease?

A 
Bloods 
Blood Film
Sickle Solubility Test 
Haemoglobin Electrophoresis 
Hip X-Ray
MRI or CT head
25
Q

What bloods do you do for Sickle Cell Disease?

A

FBC

U&Es

26
Q

What do you look for on a FBC for Sickle Cell Disease?

A

Low Hb
Reticulocytes:
- HIGH: in haemolytic crises
- LOW : in aplastic crises

27
Q

What do you see on a Blood Film for Sickle Cell Disease?

A

Sickle Cells
Anisocytosis (variation in size of red cells)
Features of hyposplenism

28
Q

What are the features of hyposplenism that you see on a Blood Film for Sickle Cell Disease?

A

Target Cells

Howell-Jolly bodies

29
Q

What happens in the Sickle Solubility Test for Sickle Cell Disease?

A

Dithionate is added to the blood

In sickle cell disease you get increased turbidity

30
Q

What happens in Haemoglobin Electrophoresis for Sickle Cell Disease?

A

Shows HbS
Absence of HbA (if homozygous HbS)
High HbF

31
Q

What do you see on a Hip X-Ray for Sickle Cell Disease?

A

Femoral Head is a common site of avascular necrosis

32
Q

When do we do a MRI or CT Head for Sickle Cell Disease?

A

If there are neurological complications

33
Q

What is the Acute Management Plan (Painful Crises) for Sickle Cell Disease?

A

Oxygen
IV Fluids
Strong analgesia (IV Opiates)
Antibiotics

34
Q

What is the general management plan for Sickle Cell Disease?

A 
Infection Prophyaxis 
Folic Acid 
Hydroxyurea/Hydroxycarbamide 
Red Cell Transfusion 
Advice 
Surgical Management Plan
35
Q

What is the Infection Prophylaxis treatment for Sickle Cell Disease?

A 
Penicillin V
Regular vaccinations (particularly against capsulated bacteria e.g. pneumococcus)
36
Q

When do you give Folic Acid for Sickle Cell Disease?

A

If severe haemolysis or in pregnancy

37
Q

Why do we give Hydroxyurea/Hydroxycarbamide for Sickle Cell Disease?

A

Increases HbF levels

Reduces the frequency and duration of sickle cell crisis

38
Q

When do we do Red Cell Transfusion for Sickle Cell Disease?

A 
For SEVERE anaemia 
Repeated transfusions (with iron chelators) may be required in patients suffering from repeated crises
39
Q

What advice do you give for Sickle Cell Disease?

A

Avoid precipitating factors, good hygeine and nutrition, genetic counselling, prenatal screening

40
Q

What is the surgical management plan for Sickle Cell Disease?

A

Bone Marrow Transplantation

Joint replacement in cases with avascular necrosis

41
Q

What are the complications of Sickle Cell Disease?

A 
Aplastic Crises 
Haemolytic Crises 
Pigment Gallstones 
Cholecystitis 
Renal papillary necrosis 
Leg Ulcers 
Cardiomyopathy
42
Q

What is the significance of Aplastic Crises of Sickle Cell Disease?

A

Infectionw with Parvovirus B19 can lead to a temporary cessation of erythropoiesis (which can cause red cell count to plummet in sickle cell patients because their red cells have a shortened life span and can’t tolerate a cessation of erythropoiesis)

43
Q

What is the prognosis for patients with Sickle Cell Disease?

A

Most patients with sickle cell disease who manage their disease well will survive until around the age of 50 yrs

44
Q

What is mortality usually the result of in Sickle Cell Disease?

A

Pulmonary or neurological complications in ADULTS

Infection in CHILDREN

Haematology (24 decks)

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