Sickle Cell Anaemia Flashcards
what inheritance pattern does sickle cell anaemia follow
autosomal recessive inheritance
what is sickle cell anaemia
chronic, autosomal recessive condition where there is a single gene defect In one of the beta chains of Hb resulting in sickled haemoglobin being inherited
what is sickle cell trait
sickle cell trait is if someone is heterozygous; carrier of HbS
what is sickle cell disease
group of inherited red blood cell diseases including HbS, HbC and beta thalassaemia
what does the mutation cause
valine replaces glutamic acid on the beta amino acid chain at position 6
what does sickling cause (features of sickled red blood cells)
more fragile, more flexible, crescent shaped, occludes small blood vessels which can lead to Ischaemia, red cell haemolysis (about 20 day life cycles)
why does hypoxia lead to more sickling (positive feedback)
deoxygenation of the red blood cells cause them to become sickle shaped
what factors precipitate sickling
hypoxia, infection, dehydration, acidosis
where is sickle cell common
africa, Caribbean where malaria is prevalent
presenting symptoms of sickle cell (vasoocclusion or infarction)
autosplenectomy (infarction of splenic atrophy)- increased risk of infections
abdominal pain
bone pain
myalgia/ arthralgia
CNS (fits and strokes)
retinopathy
presenting symptoms (sequestration crisis)
sequestration is where red blood cells pool in the spleen
if sequestration occurs in lungs there will be breathlessness, cough, pain and fever
signs on physical examination of sickle cell (vasoocclusion or infarction)
joint/ muscle tenderness,
short digits due to infarctions
retina - cotton wool spots showing proliferative retinopathy
signs on physical examination of sickle cell (sequestration)
organ hypertrophy,
priapism (persistent painful erection)
investigations for sickle cell
FBC (low Hb, high numbers of reticulocytes)
blood film will show sickled cells and signs of hyposplenism (Howell-Jolly cells)
haemoglobin solubility testing
Hip X-Ray
CT/MRI head
treatment of acute crisis
STRONG IV analgesia, oxygen, IV fluids, antibiotics
