Normocytic anaemia Flashcards
Give 5 causes of normocytic anaemia
A – Acute blood loss
A – Anaemia of chronic disease (CKD)
A – Aplastic anaemia
H – Haemolytic anaemia
H – Hypothyroidism
What are some hereditary causes of haemolytic anaemias
- membrane: hereditary spherocytosis/elliptocytosis
- metabolism: G6PD deficiency
- haemoglobinopathies: sickle cell, thalassaemia
What are the immune causes of acquired haemolytic anaemia (Coombs-positive)?
- Autoimmune: Warm or cold antibody types.
- Alloimmune: Transfusion reaction, haemolytic disease of the newborn.
- Drug-induced: Methyldopa, penicillin.
What are the non-immune causes of acquired haemolytic anaemia (Coombs-negative)?
- Microangiopathic haemolytic anaemia
- Prosthetic heart valves
- Paroxysmal nocturnal haemoglobinuria
What type of genetic condition is sickle-cell anaemia?
autosomal recessive condition
What is the normal haemoglobin type and the haemoglobin types in sickle-cell disease?
- Normal haemoglobin: HbAA
- Sickle-cell trait: HbAS
*Homozygous sickle-cell disease: HbSS - A milder form can occur with HbSC (when HbS and HbC are inherited).
When do symptoms of sickle-cell anaemia typically develop in homozygotes (HbSS)?
Symptoms typically develop at 4-6 months of age when abnormal HbSS molecules replace fetal haemoglobin
Explain the pathophysiology of sickle-cell anaemia
- affects the gene for beta-globin (polar amino acid glutamate is substituted by non-polar valine in each of the two beta chains)
- in the deoxygenated state the HbS molecules polymerise and cause RBCs to sickle
- sickle cells are fragile and haemolyse; they block small blood vessels and cause infarction
What is the definitive test for diagnosing sickle-cell disease?
haemoglobin electrophoresis.
What are the general management options for sickle-cell disease
- hydroxycarbamide: increases the HbF levels and is used in the prophylactic management of sickle cell anaemia to prevent painful episodes
- pneumococcal polysaccharide vaccine every 5 years
- antibiotic prophylaxis (penicillin V)
- blood transfusions
- stem cell transplant (curative)
Give 4 types of sickle-cell crises
- vaso-occlusive crises
- acute chest syndrome
- aplastic crises
- Sequestration crises
What triggers thrombotic (vaso-occlusive) crises in sickle-cell anaemia?
- Infection
- Dehydration
- Deoxygenation (e.g., high altitude)
How are thrombotic (vaso-occlusive) crises diagnosed?
diagnosed clinically, though tests may be performed to exclude other complications
What is acute chest syndrome in sickle-cell anaemia?
occurs when vaso-occlusion within the pulmonary microvasculature causes infarction in the lung parenchyma
How does acute chest syndrome present in sickle-cell crises
- dyspnoea
- chest pain
- cough
- new pulmonary infiltrates on chest x-ray
- low pO2
How is acute chest syndrome managed?
- Pain relief
- Respiratory support (e.g., oxygen + incentive spirometry)
- Antibiotics/ antivirals
- Transfusion (to improve oxygenation)
- Fluids
What causes aplastic crises in sickle-cell anaemia?
Aplastic crises are usually triggered by parvovirus B19 infection, leading to a sudden fall in haemoglobin and bone marrow suppression, which results in a reduced reticulocyte count.
What causes sequestration crises in sickle-cell anaemia
sickling of RBCs within organs such as the spleen or lungs causes pooling of blood with worsening of anaemia
* associated with an increased reticulocyte count
