sickle cell anaemia

Question 1

what is sickle cell anaemia characterised by

Answer 1

Anaemia with normal sized red blood cells. - all normocytic

An inherited gene abnormality means red blood cells “sickle” during hypoxia.

Question 2

pathophysiology of sickle cell anaemia

Answer 2

1. base substitution on chromosome 11 means an amino acid in the HbB chain goes from GLU to VAL, producing HbS (haemoglobin S) instead.
2. two genes code for beta-globin (HbB).
3. one mutation gives you sickle cell trait, which is a less severe or asymptomatic form of the disease
4. two mutations give you sickle cell disease, the full-blown
   version discussed here.
5. This leads to polymerisation (incorrect folding) of the haemoglobin chain during states of hypoxia.
6. Sickle RBCs can get lodged in various tissues, causing sickle
   cell crises.
7. Sickle cells are also haemolysed
   regularly by the spleen.
8. Rapid RBC turnover means bone marrow can’t keep up with production, leading to normocytic anaemia.

Question 3

inheritance pattern of sickle cell anameia

Answer 3

autosomal reccessive

Question 4

where is sickle cell anaemia common

Answer 4

Middle Eastern, African,
and subtropical descent.

The “trait”
phenotype provides resistance
against severe malaria.

Question 5

signs and symptoms of sickle cell anaemia

Answer 5

• Fatigue
• Symptoms of sickle cell crises
• Pallor
• Splenomegaly
• Gallstones
• Jaundice

Question 6

investigations for sickle cell anaemia

Answer 6

• FBC, U+E: normocytic, normochromic
  anemia
• Blood film: sickle cells seen
• Globin electrophoresis: shows HbS
• Screening: at-risk parents before week 10 of pregnancy (UK)
• Newborn spot test (UK)

Question 7

treatment for an acute sickle cell attack

Answer 7

IV Fluid + Analgesia (NSAIDs) + O2 + Antibiotics (Infections only)

Question 8

other treatment options for sickle cell anaemia

Answer 8

• Avoiding sickle cell crisis triggers
• Hydroxycarbamide (stimulates HbF) + Folic Acid Supplements
• Symptomatic treatment e.g. blood transfusions and Fe Chelation for severe anaemia

Question 9

what are sickle cell crisisis

Answer 9

complications of sickle cell anaemia

They can be triggered by infection, a drop in temperature, dehydration, etc.
They are treated conservatively.

Question 10

give 4 sickle cell crisises

Answer 10

1. vaso occlusive
2. acute chest syndrome
3. splenic sequestration
4. aplastic crisis

Question 11

what is a vaso occlusive crisis

Answer 11

sickle RBCs get lodged in tissues, causing ischaemia and
pain and triggering a systemic inflammatory response.

o Presents with inflammation signs and intense full-body pain

Question 12

what is acute chest syndrome

Answer 12

pulmonary blood vessels are occluded by sickle RBCs, leading to lung ischaemia and hypoxia. (Requires blood transfusion)

presents with Chest pain, shortness of breath, coughing, vaso-occlusive crisis
symptoms

Question 13

what is splenic sequestration

Answer 13

sickle RBCs increasingly lodge and pool in the spleen.

presents with Severe anaemia, hypovolaemic shock, acute splenomegaly

Question 14

what is aplastic crisis

Answer 14

Parvovirus B19 infection rapidly slows bone marrow haematopoiesis.
RBC destruction > RBC synthesis.

presents with Severe acute anaemia

Question 15

long term complications of sickle cell anaemia

Answer 15

Ischaemia caused by sickle cell disease can cause complications in any organ where blood is involved.

Splenic ischaemia and avascular necrosis are common.