Anaemia Flashcards
Describe the structure of haemoglobin
- 4 polypeptide globin chains
- Each chain is complexed to a haem molecule
- Haem is an iron containing compound
What is anaemia?
A reduction of haem and/or globin
What haemoglobin level is seen in anaemia?
How is anaemia classified?
Men: Hb <130g/L
Women: <120g/L
Anaemia is classified based on mean corpuscular volume (MCV)
Classifications of anaemia
- Microcytic (MCV <80fL)
- Normocytic (MCV 80-95fL)
- Macrocytic (MCV >95fL)
Causes of microcytic anaemia
- Iron deficiency anaemia
- Thalassaemia
- Anaemia of chronic disease
- Sideroblastic anaemia
Symptoms of anaemia
- Fatigue
- SOB exertion
- Chest pain
- Palpitations
Signs of anaemia
- Tachycardia
- Tachypnoea
- Hypotension
- Pallor
History taking in anaemia
- History of presenting complaint
- Symptoms of anaemia (fatigue, SOB, palpitations, chest pain)
- Screen for areas of blood loss: GI, respiratory, urinary tract, menstrual
- Alarm symptoms: weight loss, loss of appetite, night sweats, lymphadenopathy
- Dietry history
- Past medical history
- Chronic disease
- Trauma
- Family history
- Inherited disorders eg haemaglobinopathies
General principles of investigations in anaemia
Bloods:
- FBC: reduced Hb, assess MCV
- Blood film
- Iron studies
- B12 and folate levels
- Haemolysis screen: bilirubin, haptoglobin, COombs test
- U&Es: CKD
- TFTs: hypothyroidism
- LFTs: chronic liver disease
Imaing:
- Assess for sight of blood loss
Special tests
- Bone marrow biopsy
Definition of iron deficiency anaemia
Reduced intake, increased requirement, or increased loss of iron, leading to anaemia.
Iron is absorbed in the duodenum and is transported in the blood bound to X. It is stored intracellularly bound to Y.
X = Transferrin
Y = Ferritin
Causes of iron deficiency anaemia in infants
- Malnutrition
- Breast feeding
Causes of iron deficiency anaemia in children
- Malnutrition
- Malabsorption eg coeliac disease
Causes of iron deficiency anaemia in adults
- Peptic ulcer disease
- Menorrhagia
- Malabsorption eg coeliac disease
Causes of iron deficiency anaemia in the elderly
- Colon cancer
Clinical features of iron deficiency anaemia
- Glossitis (tongue red and stolen)
- Angular stomatitis/chelitis
- Koilonychia
- Pica
Which patients with iron deficiency anaemia would require an urgent colonoscopy?
Over the age of 60
Investigations for iron deficiency anaemia
Bloods
- FBC: microcytic anaemia (MCV <80fL)
- Blood film: hypochromic red cells, target cells
-
Iron studies:
- Ferrtitin: reduced
- Serum iron: reduced
- TIBC: increased
- Transferrin saturation: decreased
Imaging
- Endocopy if:
- Suspecting upper GI bleed or
- ≥ 60 years old with iron deficiency anaemia
Special test
- Coeliac serology (if suspecting coeliac disease)
Managment of iron deficiency anaemia
- Address the underlying cause
- Oral iron replacement
- Ferrous sulphate or ferrous fumarate
- Monitor Hb 2-4 weeks after staring and then at 2-4 months
- Treatment should continue for 3 months after anaemia corrected
- Intravenous iron replacement
- Blood transfusion
Which patients with iron deficiency anaemia should receive intravenous iron replacement?
- Not responding or intolerant to oral therapy
- Malabsorption
- Renal failure
Which patients with iron deficiency anaemia should receive a blood transfusion?
- Hb <70g/L or
- Hb <80g/L and cardiac co-morbidity
Side effects of oral iron
- Constipation
- Black stools / malaena
Definition of thalassaemia
Autosomal recessive haemoglobinopathy. There is impaired globin chain synthesis.
Epidemiology of thalassaemia
- Prevelent in areas of malaria
- Alpha thalassaemia: Asian and African
- Beta thalassaemia: Asian, Mediteranean and Middle Eastern
What are the types of normal haemoglobin? Show their structure and proportion in adults.
- HbA α2β2 90%
- HbA2 α2δ2 <2%
- HbF α2γ2 <2-5%
HbA, HbA2 and HbF in alpha thalassaemia and beta thalassaemia
- Alpha thalassaemia
- HbA = reduced
- HbA2 = reduced
- HbF = reduced
- Beta thalassaemia
- HbA = reduced
- HbA2 = increased
- HbF = increased
Alpha thalassaemia types of disease. Number of gene deletions. Effect on haemoglobin. Features of disease.
- Silent carrier:
- 1 deletion
- Normal haemoglobin
- Asymptomatic
- Trait:
- 2 deletions
- Reduced haemoglobin
- Mild anaemia
- HbH
- 3 deletions
- Greatly reduced haemaglbin
- Marked anaemia; beta chains form tetramers
- Hb Barts
- 4 deletions
- Absent haemoglobin
- Hydrops fetalis; death in utero; gamma chains from tetramers
Pathophysiology of beta thalassaemia
- 2 alleles code for beta globin production
- Gene mutations
- Raised production (β+)
- Absent production (β0)
Trait; β/β+; reduced HbA, increased HbA2 and HbF; asymptomatic or mild symptoms
Major; β0β0; absent HbA, increased HbA2 and HbF; marked anaemia
Signs of thalassaemia
- Neonatal jaundice
- Hepatosplenomeglay
- Failure to thrive
- Chipmunk facies
Investigations for thalassaemia
- Bloods:
- FBC: microcytic anaemia (MCV <80fL)
- Blood film: hypochromic red cells, target cells, Howell Jolly bodies
- Hb electrophoresis
- Imaging
- Skull x-ray: hair on end appearance
Managment of alpha or beta thalassaemia trait
- No intervention required
Managment of HbH and beta thalassaemia major
- Regular blood transfusions
- Folate supplementation: haemolysis leads to folate deficiency
- Iron chelation: desferrioxamine reduces the risk of iron overload
-
Splenectomy
- For patients with massive splenomeglay due to extramedullary haematopoiesis
- Resuting hypersplenism leads to increased haemolysis
- Stem cell transplant: Only curative option
Definition of anaemia of chronic disease
Anaemia due to inflammation mediated reduction in RBC production.
Can be microcytic or normocytic. Often starts as normocytic and becomes microcytic.
Epidemiology of anaemia of chronic disease
- Second most common anaemia worldwide
- Multiple causes
Causes of anaemia of chronic disease
- Autoimmune disorders eg rheumatoid arthritis
- Chronic infection
- Chronic disease eg CKD, heart failure
- Malignancy
- Major trauma
Investigations for anaemia of chronic disease
-
Bloods
-
Iron studies
- Ferritin: raised
- Serum iron: reduced
- Transferrin saturation: reduced
- TIBC: reduced
- Inflammatory markers: raised
-
Iron studies
Definition of sideroblastic anaemia
Anaemia due to defective haem synthesis within the mitochondria
Causes of sideroblastic anaemia
- Congenital: X-linked recessive enzyme deficiency
- Vitamin B6 deficiency
- Lead poisoning
- Chronic alcoholism
Investigations in Sideroblastic anaemia
- FBC: microcytic anaemia
- Blood film: ringed sideroblasts
- Iron studies
- Ferritin: increased
- Serum iron: increased
- Transferrin saturation: increased
- TIBC: reduced
