SICKLE CELL DISEASE II Flashcards
(clinical features, diagnosis and management)
Result of sickling in Sickle cell disease results in?
These physiological changes result in a disease with the following cardinal signs:
- Anaemia
i. hyperhaemolytic crisis,
ii. Sequestration crisis,
iii. Aplastic crisis
iv. Megaloblastic arrest - Painful vasoocclusive crisis, and
- Multiple organ damage with microinfarcts, including heart, skeleton, spleen, and central nervous system
Clinical presentation SCD
- The overall clinical picture is as a result of increased haemolysis and vaso-occlusion.
- The disease is more severe in patients with HbSS or HbS β0-thalassaemia than in those with HbS β+-thalassaemia or HbSC disease.
- The Arab–Indian haplotype produces a less severe disease than the African haplotypes.
- The high HbF level observed in hereditary persistence of fetal haemoglobin (HPFH) is associated with very mild disease.
- In countries with inadequate healthcare, SCD is associated with high mortality in the first 3 years of life as a result of sepsis and splenic sequestration.
- In the developed world, the typical patient with SCD has moderately severe anaemia, leads a relatively normal life interrupted by ‘crises’ as a result of vaso-occlusion, and
- Has a life expectancy of over 45 years.
Varied features of SCD: Under 6 month of age
Features can vary with age:
Under 6 month of age : Pallor, Jaundice, Hepatosplenomegally, Hand- foot syndrome ( painful swelling of One hand, One hand + foot same side, One hand + foot opposite side.
Varied features of SCD: Under 2 years of age
Under 2 years :
Incidental Anaemia,
Hand-foot syndrome (Dactylitis),
Varied features of SCD: Children and adolescents
Children and adolescents :
Chronic leg ulcers,
Priapism
Proliferative sickle retinopathy,
Bone pain crisis, Femoral head necrosis (avascular)
Osteomyelitis,
Acute chest syndrome.
Varied features of SCD: Adults
Adults :
Painful Vasoocclusive, crisis,
less hyperhaemolytic episodes,
end organ damage ( renal failure)
The clinical manifestations are usually triggered by what?
infections, stress , dehydration and other factors.
What are reasons for infections in SCD?
REASONS FOR INFECTIONS includes :
Relative asplenia (autosplenectomy)
Relative tissue hypoxia
Iron overload
Defective complement system
Clinical presentation: Growth and development
Children with SCA are born with normal weight but fall behind other children by the end of the first year.
The weight deficit persists through adulthood and imparts a thin habitus to the typical patient, although obesity is seen in some cases.
The rate of growth is lower than normal in SCA patients, and the pubertal growth spurt is delayed by 1–2 years, but the final adult height is normal.
Delays also occur in skeletal maturation and onset of puberty, and female patients achieve menarche 1–2 years later than their peers.
Clinical presentation: Neurological complications
Neurological complications
Are an important cause of morbidity in SCD.
Transient ischaemic attacks or stroke due to cerebral infarction or haemorrhage occur in 25% of patients with SCD.
The risk of stroke is increased
with lower baseline haemoglobin,
low HbF level,
high leucocyte count or
high systolic blood pressure.
Clinical presentation: pulmonary complications
Pulmonary complications
Acute and chronic pulmonary complications are the leading cause of death in older patients.
The acute chest syndrome is characterized by hypoxia, tachypnoea, fever, chest pain and pulmonary infiltrate on chest radiographs.
The pathogenesis of acute chest syndrome involves vaso-occlusion, infection or both.
Infections due to Mycoplasma, Chlamydia, Legionella, pneumococcus, H. influenzae and viruses are more likely in children.
Clinical presentation: Hypoxia
Hypoxia due to acute chest syndrome can result in widespread sickling and vaso-occlusion, with risk of multi-organ failure.
Clinical presentation: Priapism
Priapism
Priapism occurs in two-thirds of males with SCD, with a peak incidence in the second and third decades.
It is caused by vasoocclusion leading to obstruction of venous drainage from the penis.
Clinical presentation: Liver
The liver can be affected by:
intrahepatic trapping of sickle cells, transfusion-acquired infection and transfusional haemosiderosis.
Episodes of cholestasis due to intrahepatic sickling can lead to liver failure in rare instances.
Pigmented gallstones are seen in two-thirds of patients, particularly those with HbSS, and can occur in young children.
Discuss the sickle cell trait
Sickle cell trait (HbAS) is a benign condition that has no haematological manifestations and is associated with normal growth and life expectancy.. Impaired urine-concentrating ability and haematuria can occur.
Discuss the HbSC disease
HbC is found among individuals of African descent and the compound heterozygote state HbSC accounts for 25–50% of patients with SCD.
The vaso-occlusive complications seen in patients with HbSC resemble those of HbSS but are less severe.
Splenomegaly and the risk of sequestration can persist into adult life.
Of particular note is the higher incidence of proliferative retinopathy in HbSC beginning in the second decade.
Peripheral blood smear reveals frequent target cells, intraerythrocytic crystals and rare sickle cells.
Sickle cell–b-thalassaemia
Sickle cell–β-thalassaemia compound heterozygotes account for less than 10% of patients with sickle syndromes.
The majority of these patients have the β+-phenotype, with the proportion of HbA ranging from 3% to 25%.
The clinical phenotype is mild and disease severity correlates with the amount of HbA present.
The clinical manifestations of less frequent HbS-β0 genotype are similar in severity to those of HbSS.
Sickle cell anaemia with coexistent a-thalassaemia
Co-inheritance of α-thalassaemia (–α/αα or –α/–α) with SCD is common, and such patients have less severe anaemia and demonstrate hypochromia and microcytosis.
In general, the clinical severity is similar to that seen in HbSS patients with a normal complement of α-globin genes.
