Normocytic Anaemia Flashcards
Give 3 causes of normocytic anaemia.
- Acute blood loss / bleeding
- Anaemia of chronic disease (80% is normocytic)
- Hypothyroidism
- Haemolytic anaemia
- Bone marrow failure; - renal failure (decreased erythropoietin)
- Pregnancy
Define haemolytic anaemia.
Where there is destruction of RBCs (haemolysis) leading to anaemia.
Can either be caused by inherited conditions or acquired conditions.
Name 3 categories of inherited causes of haemolytic anaemia.
- Enzymopathies (Enzyme defects)
- Membranopathies (Membrane defects)
- Haemoglobinopathies (Abnormal Hb production)
Give 2 examples of enzymopathies for haemolytic anaemia.
- G6PD Deficiency
- Pyruvate kinase deficiency
Give 2 examples of membranopathies for haemolytic anaemia.
- Hereditary Spherocytosis
- Hereditary Elliptocytosis
Give 2 examples of haemoglobinopathies for haemolytic anaemia.
- Thalassaemia
- Sickle Cell Anaemia
Give 5 examples of acquired conditions that cause haemolytic anaemia.
- Autoimmune haemolytic anaemia
- Alloimmune haemolytic anaemia (transfusions reactions and haemolytic disease of newborn)
- Paroxysmal nocturnal haemoglobinuria
- Microangiopathic haemolytic anaemia
- Prosthetic valve related haemolysis
Give the 3 main signs + symptoms for haemolytic anaemia.
- Pallor due to Anaemia -> due to the reduction in circulating RBCs
- Splenomegaly -> as the spleen becomes filled with destroyed RBCs
- Jaundice -> as bilirubin is released during the destruction of RBCs
What is sickle cell disease?
A haemoglobin disorder of quality. HbS polymerises -> sickle shaped RBC.
What is the advantage of being a carrier of sickle cell disease?
Carriage offers protection against falciparum malaria.
What gene causes sickle cell disease and on which chromosome?
An abnormal gene for β-globin on CH 11
Describe the difference between sickle cell trait and sickle cell disease.
2 abnormal copies = homozygous HbSS = sickle cell disease.
1 abnormal gene = heterozygous HbAS = sickle cell trait (carrier) = usually asymptomatic.
Why is sickle cell not diagnosed until 6 months after birth?
Not diagnosed until 6 months after birth because:
= HbF is not affected by sickle cell anaemia as it is made up of 2 alpha and 2 gamma chains.
Why does sickle cell anaemia not present until after 6 months of age?
HbF is not affected by sickle cell anaemia as it is made up of 2 alpha and 2 gamma chains.
What is the risk factor for sickle cell anaemia?
Family history
Describe the inheritance pattern of sickle cell disease.
Autosomal recessive. Sickle cell disease is homozygous SS.
What is the pathogenesis of sickle cell anaemia?
HbS polymerizes if hypoxia/acidosis causing RBCs to sickle - rigid, fragile cells that occlude small vessels and have short lifespan (haemolyse).
If both parents are carriers of the sickle trait, what is the chance that their first child will have sickle cell disease?
Their offspring have a 1/4 chance of being affected with a sickle cell disease. (50% chance of being a carrier).
How long do sickle cells last for?
5-10 days - this explains why sickle cell disease is described as haemolytic.
What is the significance of parvovirus for someone with sickle cell disease?
Parvovirus is a common infection in children. It leads to decreased RBC production and can cause a dramatic drop in Hb in patients who already have a reduced RBC lifespan. This can be dangerous for someone with sickle cell.
What factors can precipitate a sickle cell crisis?
CHIDS:
Cold
Hypoxia (including extreme exercise)
Infection
Dehydration
Stress
Give 4 acute complications of sickle cell disease.
- Very painful crisis.
- Stroke in children.
- Cognitive impairment.
- Infections.
Give 4 complications for chronic sickle cell anaemia/disease.
o Renal impairment.
o Pulmonary hypertension.
o Joint damage, bone problems, leg ulcers.
o Poor growth.
o Gallstones.
o Lung fibrosis.
o Neurological complications – TIA, fits, coma, cerebral infarction.
o Cardiac – cardiomegaly, MI, arrythmias, Fe-overload cardiomyopathy
Give the 4 different types of crisis that can happen in sickle cell anaemia.
- Splenic sequestration crisis (acute)
- Aplastic / Bone Marrow crisis
- Haemolytic crisis
- Vaso-occlusive crisis
What is splenic sequestration?
A type of sickle-cell crisis:
- Vaso-occlusion produces acute painful enlargement of spleen.
- Pooling of RBCs in spleen = hypovolaemia = circulatory collapse and death.
- Immediate transfusion needed.
Describe vaso-occlusive crises seen in sickle-cell anaemia.
Severe pain due to effect on marrow of microvascular occlusion. Acutely painful hands and feet.
Specific signs + symtoms:
Dactylitis
Visual floaters
Chest/abdominal pain (mesenteric ischaemia)
Chronic renal failure.
Avascular necrosis femoral head/bone infarcts.
General signs + symptoms:
Parent with sickle cell anaemia/trait
Symptoms of anaemia + haemolysis = jaundice, pallor, lethargy, tachycardia.
For sickle cell crisis, what syndrome can be caused?
Acute Chest Syndrome (ACS).
Describe ACS.
A vaso-occlusive crisis of the pulmonary vasculature.
What can ACS be caused by? Give 3 examples.
- Infection (due to Chlamydia, mycoplasma and Streptococcus pneumoniae)
- Fat embolism from necrotic bone marrow
- Pulmonary infarction due to sequestration of sickle cells (where sickle cells get trapped in the pulmonary vasculature)
For ACS, what are the 2 most common causes of death?
- Pulmonary hypertension
- Chronic lung disease
What symptoms can ACS result in? Name 3.
SOB, chest pain, hypoxia
What test is diagnostic for sickle cell anaemia?
Hb electrophoresis
What are the investigations for sickle cell anaemia?
- FBC
- Low Hb -> in the range of 60-80 g/L
- Raised reticulocyte count - Blood film
- Sickle cells and target cells (pale centre)
- Howell-Jolly bodies - Sickle solubility test
- Positive result = HbSS/HbAS instead of HbA - Hb electrophoresis = DIAGNOSTIC!!!
- Distinguishes HbSS and HbAS
What is seen after doing a blood film for sickle cell anaemia?
- Howell-Jolly bodies
- Sickle cells
What drug can be used to prevent painful crises in people with sickle cell anaemia?
Hydroxycarbamide.
Give the management for acute sickle cell anaemia.
Acute painful attacks:
1. IV fluids
2. Analgesia – morphine, codeine, paracetamol and NSAIDs
3. Oxygen and antibiotics, if required
Give the management for sickle cell anaemia.
- Blood transfusion given for:
*Acute chest syndrome, Acute anaemia due to acute splenic sequestration, Aplastic crisis, Stroke, Heart failure
(Note: increased risk of iron overload)
- Oral HYDROXYCARBAMIDE:
- Increases HbF concentrations and to try prevent painful crises
- Need monthly blood tests - Regular vaccinations e.g. pneumococcal vaccine
- Penicillin prophylactically = lifelong phenoxymethylpenicillin
→ risk of infection - Stem cell / bone marrow transplant → curative
What can be given orally to increase HbF and for the prevention painful crises in sickle cell anaemia?
Oral Hydroxycarbamide
Describe the inheritance pattern for membranopathies.
Autosomal dominant.
Name 2 common membranopathies.
- Spherocytosis.
- Elliptocytosis.