Sickle-Cell Anaemia Flashcards
Is it autosomal dominant or recessive?
Recessive
It causes abnormally-shaped sickle cell Hb.
What 3 things does this cause?
Breaks down easily - haemolytic anaemia
Occludes microvascular
Sequestered in the liver and spleen, the latter causing splenic dysfunction and immunosuppression.
The beta chain is affected in sickle cell.
The average lifespan of HbA is 120 days. What is the average life span for HbS?
20 days
What continent is it common in?
Africa
What infectious disease does a sickle cell trait (not disease) protect you from?
What situations may someone with a trait become symptomatic?
Malaria
In hypoxia (e.g. unpressurised aircraft or anaesthesia) So all those with African descent need a sickle cell trait test.
Chronic features:
What S+S do you find due to the haemolysis?
Why do they get chronic pain?
They get painful dactylitis.
- What is it?
- What are patients sometimes described as having?
- Around what age does it occur?
Why do they get splenomegaly?
Pallor
Fatigue
Jaundice
In sickle cell anaemia patients, neuropathic pain is either caused by the occlusion of blood vessels that supply nerves, resulting in nerve cell damage, or by persistent chronic pain that results in inflammation.
Swelling of foot or hand bones
Sausage fingers
<3 yrs old
Sickle cells can block the blood vessels leading out of the spleen. When this happens, blood stays in the spleen instead of flowing through it. This causes the spleen to get bigger, and the blood counts to fall. This is called a splenic sequestration
Chronic features:
What GI pathology could chronic haemolysis lead to?
How does it affect the CV system?
Pigmented gallstones
High cardiac output - due to chronic anaemia:
- Cardiomegaly
- Murmur
Sickle cell crisis - vaso-occlusive (painful) crisis:
What triggers a shift in the O2 dissociation curve making a crisis more likely as the RBC’s sickle? - 3
What triggers a crisis by causing vasoconstriction? - 4
Where is the occlusion more likely to happen leading to severe pain?
Where else does occlusion happen?
Why can it present as an acute abdomen?
How may CNS infarction present?
What joint is it at particular risk of necrosis?
What may happen in the lower legs?
They can present with priapism. What is it?
Hypoxia
Fever - infection
Acidosis
Cold
Dehydration
Stress
Pain
Bones - especially limbs
Chest and abdomen
Due to mesenteric ischaemia
Seizures
Cognitive defects
Strokes
Femoral head necrosis
Leg ulcers
Prolonged erection - due to microvascular occlusion
Sickle cell crisis - Acute chest syndrome crisis:
What sort of symptoms will they present with?
Why does this happen?
Chest pain SOB Cough Fever Lung crackles Tender ribs
Due to chest infiltrates
Sickle cell crisis - Aplastic crisis:
What virus is this due to?
What actually happens leading to a crisis?
Parvovirus B19
Parvovirus B19 is the most common agent responsible for erythema infectiosum, also known as ‘Fifth disease’. The characteristic rash in Fifth disease is the classic ‘slapped cheek’ appearance. In patients with sickle cell disease, Parvovirus B19 is associated with aplastic crisis and bone marrow suppression. The full blood count would show a lower than normal haemoglobin with a low reticulocyte count. Platelets and white cells are also affected.
Sudden reduction n marrow production especially RBCs
Sickle cell crisis - Sequestration:
What age group does this usually happen in and why?
What is sequestration?
Children as in adults, the spleen becomes atrophic
There is the pooling of blood in the spleen and/or liver, with organomegaly, severe anaemia and shock
How does pregnancy affect sickle cell anaemia?
Makes it worse
High risk of obstetric complications - miscarriage, PET, IUGR
Investigations - Diagnostic Testing:
Usually made at birth!!
A sickle solubility test is used. What is it?
Once it has been identified, what test can be used to distinguish between HbSS and HbAS?
The sickle cell solubility test is a qualitative test based on the relative insolubility of haemoglobin S compared to other haemoglobin variants. A positive test indicates the presence of haemoglobin S or non-S sickling haemoglobin.
Hb electrophoresis - a blood test that measures different types of a protein called haemoglobin in your red blood cells.
Investigations - Bloods:
Anaemia - what 4 things would you do?
Why are U&E and LFTs done?
FBC (Low Hb)
Reticulocytes raised - due to increase production
Blood film
Iron studies
If there are complications - sequestration
Management - Preventative and Lifestyle:
How often are they checked up?
What is done to look for risk of strokes?
Why should they avoid alcohol?
Why should they avoid smoking?
What immunisation should they have to prevent infections? Why are these given?
Annually
Transcranial doppler US
Alc causes dehydration which triggers crisis
Smoking triggers acute chest syndrome
Flu annually
Hep B
Pneumococcal every 5 yrs
As they are immunosuppressed due to splenic disease from sequestration
