Sickle cell anemia Flashcards
Sickle-cell anaemia is an
autosomal recessive condition that results for synthesis of an abnormal haemoglobin chain termed HbS
normal haemoglobin
HbAA
sickle cell trait
HbAS
homozygous sickle cell disease
HbSS
Some patients inherit one HbS and another abnormal haemoglobin (HbC) resulting in
HbSC
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
Sickle cell anaemia is characterised by periods of
good health with intervening crises
types of crises are recognised?
thrombotic, ‘vaso-occlusive’, ‘painful crises’
acute chest syndrome
anaemic:
aplastic
sequestration
infection
Thrombotic crises/ ‘vaso-occlusive’, ‘painful crises’ precipitated by ?
infection, dehydration, deoxygenation (e.g. high altitude)
Thrombotic crises/ ‘vaso-occlusive’, ‘painful crises’ diagnosed ?
clinically
infarcts occur in various organs including ?
bones (e.g. avascular necrosis of hip, hand-foot syndrome in children, lungs, spleen and brain
Acute chest syndrome?
vaso-occlusion within the pulmonary microvasculature → infarction in the lung parenchyma
cxr in acute chest syndrome ?
pulmonary infiltrates on chest x-ray
chest syndrome Mx
pain relief
respiratory support e.g. oxygen therapy
antibiotics: infection may precipitate acute chest syndrome and the clinical findings (respiratory symptoms with pulmonary infiltrates) can be difficult to distinguish from pneumonia
transfusion: improves oxygenation
Aplastic crises caused by
parvovirus
Diagnosis of aplastic crisis ?
sudden fall in haemoglobin
bone marrow suppression causes a reduced reticulocyte count
Sequestration crises clinical features ?
splenomegaly
Monitoring of blood of sequestration crisis ?
increased reticulocyte count
x
x
x
Sickle cell patients should be started on long term
hydroxycarbamide - reduce the incidence of complications and acute crises
