RBC and Hb Disorders Flashcards
What is sickle cell anaemia?
Autosomal recessive
If you have one recessive allele, then you are protected against malaria.
More commonly seen in African, Indian, and middle eastern populations
What causes the sickled red blood cells?
Mutation in the beta globin resulting in beta chains from different Hb sticking together when Hb is in the T state resulting in the red cells taking on a sickled shape. These red cells get stuck in small blood vessels leading to ischaemia.
What are the signs and symptoms of sickle cell disease?
Symptoms begin at around 5 months
Anaemia – although this is chronic and usually asymptomatic
Jaundice
Children usually have multiple splenic infarction before 2 years and so have an atrophic spleen by adult hood increasing their risk of encapsulated bacterial infections. Poor growth Chronic renal failure Gall stones Retinal disease Iron overload
Sickle crisis
What are the 4 main sickle cell crisis?
Sickle Cell crisis – induced by increasing the proportion of Hb in the T state i.e. smoking, obesity, infection, temperature changes, high altitude, dehydration etc.
- Vaso-occlusive crisis – very painful, especially in the marrow. Triggered by cold, dehydration, infection or hypoxia. Hands and feet swelling and pain in younger patients. Abdominal pain due to mesenteric ischaemia. Stroke, seizures and cognitive impairment mostly in children.
- Aplastic crisis – due to parvovirus infection causing reduced marrow function – self-limiting after 2 weeks but transfusion may be required.
- Sequestration crisis – mainly children (adults usually have a atrophic spleen). Blood pools in the spleen and liver causing severe anaemia and shock – admit for transfusion.
- Acute chest syndrome – dyspnoea, chest pain, pulmonary infiltrates and low pO2 – most common cause of death after childhood.
How should suspected sickle cell disease be investigated?
Simple blood test usually done at birth
Can do blood film
How is sickle cell disease managed?
Prevent sickle cell crisis by vaccinating, prophylactic antibiotics, high fluid intake and folic acid supplements.
Regular and PRN morphine but be aware for addiction
Blood transfusion when indicated
Malaria prevention (in sickle cell disease you are more prone)
Bone marrow transplant if indicated
Hydroxyurea to encourage foetal Hb
How are sickle cell crisis managed?
Crisis Management Analgesia – opiates Rehydrate and keep warm Oxygen Consider antibiotics and sepsis screen Group and save and cross match for blood transfusion
What are spherocytosis and Elliptocytosis?
Definition – abnormality in red cell cytoskeleton causing abnormal shape
Epidemiology
Rare – 1 in 10000 have it but 90% of these will be asymptomatic
Causes
Genetic cause and is hereditary
How does spherocytosis and elliptocytosis present?
Anaemia
Jaundice
Splenomegaly
What investigations should be used in suspected RBC disorders?
Blood film showing 25% or greater of blood cells are an abnormal shape (15% are abnormal normally).
How are RBC disorder managed?
No management simply monitor anaemia – give folate supplements and if very severe splenectomy can be useful.
What complications can occur from RBC disorders?
Increased risk of developing gallstones
Can develop a crisis if haemolysis increases for some reason and this may require a blood transfusion.
What is stomatocytosis?
This is a defect in the red blood cells ion channel causing excess salt and water to enter the cell and lyse. In this condition splenectomy is contraindicated.
What is pyropoikilocytosis?
Pyropoikilocytosis a severe form of elliptocytosis in which at infancy the red cells are sensitive to heat and lyse when they are exposed to it. As they grow this progresses into elliptocytosis.
What are thalassaemias?
Definition - lack of beta or alpha chains in haemoglobin
Epidemiology
Autosomal recessive disease
Thalassaemia is particularly common in Mediterranean and African populations
