Sickle Cell Anaemia Flashcards
Fill in the blanks. “ In sickle cell anaemia , The sickle β-globin abnormality is caused by substitution of ______ for ________ in position _______in the β chain.
The sickle β-globin abnormality is caused by substitution of VALINE for GLUTAMIC ACID in position 6 in the β chain
What is sickle cell disease?
Sickle cell disease is a group of haemoglobin disorders resulting from the inheritance of the sickle β-globin gene (Hb S).
‘The Homozygous A-T substitution in β globin gene ‘ is associated with which pathology?
Sickle Cell Anaemia
What are the different types of crises that can occur in Sickle Cell Anaemia?
Vaso-oclusive ( painful or visceral)
Aplastic
Haemolytic
Which crises is the most common in sickle cell anaemia?
Vaso-oclusive ( painful )
What are the clinical features of Vaso-occluisve (Painful ) crises in Sickle cell anaemia?
- Infarcts causing severe pain occur in the bones (hips, shoulders and vertebrae are commonly affected).
- Avascular necrosis of bones, especially of the femoral head, causes long term problems
- The ‘HAND- FOOT ’ syndrome (painful dactylitis ( swollen fingers) caused by infarcts of the small bones) is frequently the first presentation of the disease, typically before age 5, and may lead to digits of varying lengths
What occurs during the Visceral Vaso-oclusive crises?
These are caused by sickling within organs causing infarction and sequestration of blood, often with a severe exacerbation of anaemia.
- The Acute sickle chest syndrome is the most common cause of death in both children and adults
What are the clinical presentations of Acute sickle - chest syndrome?
- Dyspnoea
- Falling arterial PO2
- Chest pain
- Pulmonary infiltrates on chest X-ray
What is the required treatment for Acute sickle chest syndrome?
Treatment is with analgesia, oxygen, exchange transfusion and ventilatory support if necessary.
True or False? Aplastic crises can ONLY occur from an infection with the Parvovirus.
FALSE!! It can occur as a result of infection with parvovirus or from folate deficiency.
What are the clinical features found in an Aplastic crises?
- Sudden FALL in Haemoglobin
- Sudden FALL in Reticulocytes
What are the clinical features found in a Haemolytic crises in Sickle Cell disease?
- These are characterized by an increased rate of haemolysis and FALL in haemoglobin but RISE IN RETICULOCYTES and usually accompany a painful crisis.
What are the other clinical features of Sickle Cell Anaemia?
- Damage to brain or spinal cord ( Strokes occurs in 7% of all patients)
- Leg ulcers
- Spleen enlarged in infancy and early childhood, but later is often reduced in size as a result of infarcts (autosplenectomy)
- Pulmonary Hypertension
- Left ventricular failure
- Proliferative retinopathy and priapism ( rigid erection of penis)
- Chronic damage to the liver may occur through microinfarcts
- Pigment (bilirubin) gallstones are frequent.
- Infarction of kidney with papillary necrosis
- Chronic Renal sufficiency ( complication in adulthood)
- Iron overload from increased transfusions
- Pneumonia, UTI
- Osteomyelitis usually from SALMONELLA species.
What are the Lab findings of sickle cell anaemia?
- The haemoglobin is usually 60–90g/L – low in comparison to mild or no symptoms of anaemia.
- Sickle cells and target cells occur in the blood (Fig. Features of splenic atrophy (e.g. Howell–Jolly bodies) may also be present.
- Screening tests for sickling are positive when the blood is deoxygenated (e.g. with dithionate and disodium phosphate, Na2 HPO4).
- HPLC or haemoglobin electrophoresis in Hb SS, no Hb A is detected. The amount of Hb F is variable and is usually 5–15%; larger amounts are usually associated with a milder disorder.
What is the most common symptom of sickle cell trait ?
Haematuria
