Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Year 3 TCD > 11. Sickle Cell Anaemia > Flashcards

11. Sickle Cell Anaemia Flashcards

1
Q

What does it mean if someones RBCs are crescent shaped?

A

This is another word for sickle shaped, indicating sickle cell anaemia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the two main components in red blood cells?

A
  • Heme, containing the iron

- Globin chains, which are proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the types of globin chains?

A
  • Alpha
  • Beta
  • Delta
  • Gamma
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the normal / most common 3 haemoglobin variants

A
  • Haemoglobin F (this is featal haemoglobin)
  • Haemoglobin A (95%-98% of adults have this)
  • Haemoglobin A2 (2-3% of adult population have this)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the composition of Haemoglobin F?

A

It consists of both;

  • 2 alpha chains
  • 2 gamma chains
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the composition of Haemoglobin A?

A

It consists of both;

  • 2 alpha chains
  • 2 beta chains
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the composition of Haemoglobin A2?

A

It consists of both;

  • 2 alpha chains
  • 2 delta chains
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is Haemoglobin S?

A

This is one of several hundred abnormal forms of haemoglobin.

Specifically, it is known as sickle cell disease if you are homozygous for it.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the globin chains like in someone with sickle cell disease?

A
  • 2 abnormal beta chains (coded from chromosome 11)

- 2 normal alpha chains

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

When do the RBCs become sickle shaped in sickle cell anaemia?

A

When they have decreased amounts of oxygen (ex. during exercise, infection etc.)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is sickle cell trait?

A

This is when an individual only has 1 globin chain that is abnormal. Therefore it would be

  • 1 abnormal beta chain
  • 1 normal beta chain
  • 2 normal alpha chains
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Do those with sickle cell trait have symptoms?

A

They are normally asymptomatic.

However, if sickle-cell trait is combined with another haemoglobin mutation (ex. Hb C or thalassaemia, then they can have significant symptoms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What happens to the sickle shaped RBCs as they travel through the body?

A

Normal shape when oxygenated.

Once they become less oxygenated, they turn into sickle shapes. This can block capillaries, cause pain, aand result in decreased oxygen delivery.

As they are abnormal, they are filtered out by the reticulo-endothelial system early, meaning there is decreased red cell survival.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Are individuals with haemoglobin C symptomatic?

A

If they have only 1 mutated gene, then typically they are asymptomatic

If they have 2 mutated gene copies, then typically they are symptomatic

Similarly, if they have 1 abnormal gene, then have 1 abnormal gene for another condition (ex. sickle cell, thalassaemia etc.) then they are normally symptomatic.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is haaemoglobin SC disease? What symptoms does it cause?

A

This is when you have 1 copy of Hb S and one copy of Hb C.

On their own, they would not produce symptoms. But as they both are abnormal, together, it causes symptoms. They have

  • Mild haemolytic anaemia
  • Moderate enlargement of the spleen
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Among which group of the population is sickle cell disease most common? Why?

A

It is most common in patients from areas typically affected by Malaria (Africa, India, Middle East, Carribean).

This is because having 1 copy of Hb S (ie. having sickle-cell trait) has been proven to reduce the severity of malaria. Therefore there is a selective advantage to have sickle-cell trait, so through natural evolution, those with 1 copy have survived better, leading to a higher proportion of the population in these areas having the gene.

17
Q

When do you get tested for sickle cell disease?

A
  • Pregnant women at risk of carrying the gene are offered testing
  • Newborns are tested as part of the heel prick test at 5 days of age
18
Q

What are the key diagnostic features in someone with sickle cell anaemia?

A
  • Anaemia symptoms (fatigue, weakness)
  • Parent diagnosed with sickle cell disease / sickle cell trait / other sickle cell condition such as Hb SC
  • Persistent pain in skeleton, chest or abdomen
  • Dactylitis
19
Q

What is Dactylitis? Why does it happen in sickle-cell disease?

A

Also reffered to as Hand-foot syndrome, it is the swelling of the dorsa of the hands and feet.

It occurs due to blood vessels becoming blocked due to the sickle cells, and therefore ther is accumulation of blood in the peripheral limbs.

20
Q

What are the complications of sickle-cell anaemia?

A
  • Anaemia
  • Increased risk of infection
  • Stroke
  • Avascular necrosis in large joints such as the hip
  • Pulmonary hypertension
  • Priapism
  • Chronic kidney disease
  • Sickle cell crises
  • Acute chest syndrome
21
Q

What is priapism?

A

Painful and persistent penile erection

22
Q

What is the general management of sickle cell anaemia

Hint; general, pharmacological and other

A

General

  • Avoid dehydration and other triggers of crisis
  • Ensure vaccines are up to date

Pharmacological

  • Antibiotic prophylaxis to protect against infection with penicillin V (phenoxymethypenicillin)
  • Hydroxycarbamide can be used to stimulate production of fetal haemoglobin (HbF). Fetal haemoglobin does not lead to sickling of red blood cells. This has a protective effect against sickle cell crises and acute chest syndrome.

Infusions / Transplants

  • Blood transusions for severe anaemia
  • Bone marrow transplant can be curative
23
Q

What medication can be given to those with sickle cell anaemia? How does it work?

A

Hydroxycarbamide can be used. It stimulates production of fetal haemoglobin, which does not lead to the sickening shape

24
Q

What is meant by the term sickle cell crisis?

A

It is an umberella term for a spectrum of acute crises related to the condition ranging in severity from mild to life threatening

Examples of crises include

  • Vaso-occlusive crisis
  • Splenic sequestration crisis
  • Aplastic crisis
  • Acute chest syndrome
25
Q

How should you manage sickle cell crises?

A

There is no specific treatment for it so they are managed supportively. This includes;

  • Having a low threshold for admitting to hospital
  • Treating any infection
  • Keeping warm
  • Keeping well hydrated (IV fluids may be needed)
  • Simple analgesia (NSAIDS should be avoided if renal damage is detected)
  • Penile aspiration in the case of priapism
26
Q

What is a vaso-occlusive crisis?

A

This is otherwise known as a painful crisis.

The sickle shaped cells block capillaries causing distal ischaemia. It is brought on by dehydration and a raised haemotocrit.

Symptoms are typically pain, fever and those of the triggering infection.

27
Q

What is an example of a vasooccusive crisis in sickle cell anaemia?

A

Priapism in men, which is trapped blood in the penis causing a painful and persistent erection.

28
Q

How is priapism treated?

A

Needle aspiration of the blood from the penis. This is a urological emergency

29
Q

What is splenic sequestration crisis?

A

Splenic sequestration crisis is caused by red blood cells blocking blood flow within the spleen. This causes an acutely enlarged and painful spleen. The pooling of blood in the spleen can lead to a severe anaemia and circulatory collapse (hypovolaemic shock)

This occurs in those with sickle-cell disease due to the shape of the RBCs

30
Q

How is splenic sequestration treated?

A

Blood transufuions to treat anaemia and extra fluid resuscitation to treat hypovolaemic shock.

31
Q

How can you prevent a splenic sequestration in someone with sickle-cell disease?

A

Splenectomy. This is done in individuals who have recurrent crises.

32
Q

What is a aplastic crisis? What causes it in those with sickle-cell disease?

A

This is where there is no new creation of blood cells. It is often temporary.

This is most commonly triggered by infection with parvovirus B1

33
Q

How are aplastic crises treated?

A

Management is supportive with blood transfusions. It usually resolves spontaneously within a week.

34
Q

What is acute chest syndrome?

A

Acute chest syndrome is a term used to cover conditions characterized by chest pain, cough, fever, hypoxia (low oxygen level) and lung infiltrates. Acute chest syndrome may be the result of sickling in the small blood vessels in the lungs causing a pulmonary infarction/emboli or viral or bacterial pneumonia.

35
Q

What is required in order to diagnosis acute chest syndrome?

A
  • Fever or respiratory symptoms

- New infiltrates seen on chest x-ray

36
Q

How can the causes of acute chest syndrome be broadly split?

A
  • Infective (pneumonia, bronchiolitis etc.)

- Non-infective (pulmonary infarction or fat emboli)

37
Q

How is acute chest syndrome managed?

A

It is a medical emergency. It requires supportive management and treatment of the underlying cause:

  • Antibiotics or antivirals for infections
  • Blood transfusions for anaemia
  • Artificial ventilation with NIV or intubation may be required

Year 3 TCD (36 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions