Anaemia Revision Flashcards
What is Hb?
Protein in RBCs –> binds O2 and carries it around body
What is essential for creating Hb?
Iron
Causes of microcytic anaemia?
Mneumonic: TAILS
T - thalassaemia
A - anaemia of chronic disease
I - iron deficiency
L - lead poisoning
S - sideroblastic anaemia
What is the difference between macrocytic and megaloblastic anaemia?
Megaloblastic anaemia is a type of macrocytic anaemia.
Macrocytes are enlarged RBCs (raised MCV).
Megaloblasts are large RBC precursors due to impaired DNA synthesis, preventing the cells from dividing normally. Rather than dividing, they grow into large, abnormal cells.
What is the cause of production of megaloblasts?
Impaired synthesis of RBC DNA e.g. folate deficiency
What hormone is responsible for production of RBCs?
EPO
Treatment of anaemia caused by CKD?
EPO
What type of anaemia does CKD cause?
Typically normocytic
What is sideroblastic anaemia ?
Body produces enough iron but is unable to put it into Hb (iron levels will be normal/high).
What is the main cause of sideroblastic anaemia?
Alcohol
Mechanism of iron absorption?
1) Mainly absorbed in duodenum & jejunum
2) Requires the acid from the stomach to keep the iron in the soluble ferrous (Fe2+) form
3) When the stomach contents are less acidic, it changes to the insoluble ferric (Fe3+) form.
How can PPIs result in iron deficiency?
Reduces stomach acid - iron stays in Fe3+ form (insoluble)
How can coeliac disease or Crohn’s disease cause iron deficiency?
Inflammation of duodenum or jejunum can reduce iron absorption.
What is the formula for transferrin saturation?
Transferrin saturation = serum iron / total iron-binding capacity
What is low ferritin highly suggestive of?
Iron deficiency
N.B. Normal ferritin does not exclude iron deficiency.
Raised ferritin is difficult to interpret.
What may it be caused by (i.e. what can cause iron overload)?
- Inflammation (e.g., infection or cancer)
- Acute liver damage (the liver contains lots of iron)
- Iron supplements
- Haemochromatosis
Why should iron infusions be avoided during infections?
there is potential for it to “feed” the bacteria.
What is the most common cause of B12 deficiency?
Pernicious anaemia
What is the role of intrinsic factor?
Produced by gastric parietal cells
It is a protein that is essential for the absorption of vitamin B12 in the distal ileum.
Pathophysiology of pernicious anaemia?1
1) Autoantibodies target parietal cells and/or intrinsic factor:
a) intrinsic factor antibodies: bind to intrinsic factor blocking the vitamin B12 binding site
b) gastric parietal cell antibodies: reduced acid production and atrophic gastritis as well as reduced intrinsic factor production
2) Lack of intrinsic factor and a lack of absorption of vitamin B12.
What are the 2 major roles of vitamin B12?
1) Myelination of nerves
2) Production of RBCs
What should you always test for in patients presenting with peripheral neuropathy, particularly with pins and needles?
vitamin B12 deficiency and pernicious anaemia
What is subacute degeneration of the spinal cord?
Vit B12 deficiency results in impairment of dorsal columns, lateral corticospinal tracts and spinocerebellar tracts.
Features of subacute combined degeneration of the spinal cord?
1) dorsal column involvement
- distal tingling/burning/sensory loss is symmetrical and tends to affect the legs more than the arms
- impaired proprioception and vibration sense
2) lateral corticospinal tract involvement
- muscle weakness, hyperreflexia, and spasticity
- upper motor neuron signs typically develop in the legs first
- brisk knee reflexes
- absent ankle jerks
- extensor plantars
3) spinocerebellar tract involvement
- sensory ataxia –> gait abnormalities
- positive Romberg’s sign
What 2 autoantibodies can be used to diagnose pernicious anaemia?
1) Intrinsic factor antibodies (the first-line investigation)
2) Parietal cell antibodies
Are IF antibodies or gastric parietal cell antibodies more useful in the diagnosis of pernicious anaemia?
IF antibodies
How often is IM hydroxocobalamin given in pernicious anaemia if there are NO neuro symptoms?
3 times weekly for 2 weeks
How often is IM hydroxocobalamin given in pernicious anaemia if there are neuro symptoms?
alternate days until there is no further improvement in symptoms
Long term management of pernicious anaemia?
2-3 monthly injections of IM hydroxocobalamin for life.
Long term management of diet related B12 deficiency?
Oral cyanocobalamin or twice-yearly injections
What cancer does pernicious anaemia increase risk of?
Gastric cancer
Why is there splenomegaly in haemolytic anaemia?
Spleen becomes filled with destroyed RBCs
What will a blood film show in haemolytic anaemia?
Schistocytes (fragments of RBCs)
Inheritance of spherocytosis?
Autosomal dominant
What is the most common inherited haemolytic anaemia in northern Europeans?
Hereditary spherocytosis
What happens in hereditary spherocytosis?
It causes fragile, sphere-shaped RBCs that easily break down when passing through the spleen.
What is seen on a blood film in spherocytosis?
Spherocytes
Treatment of hereditary spherocytosis?
1) folate supplementations
2) blood transfusions when required
3) splenectomy
Why can hereditary spherocytosis predispose to gallstones?
Higher bilirubin = gallstones
What is hereditary elliptocytosis?
Hereditary elliptocytosis is similar to hereditary spherocytosis except that the red blood cells are ellipse-shaped.
The presentation and management are the same as hereditary spherocytosis.
Inheritance of hereditary elliptocytosis?
Autosomal dominant
Role of G6PD?
It is an enzyme responsible for protecting the cells from oxidative damage.
What 3 drugs are most commonly implicated in acute episodes of haemolytic anaemia in G6PD deficiency?
1) Ciprofloxacin
2) Sulfalazine
3) Sulfonylureas (e.g. gliclazide)
Why can haemolytic anaemias predispose to gallstones?
Due to raised bilirubin
How can a diagnosis of G6PD deficiency be made?
G6PD enzyme assay.
What is seen on a blood film in G6PD deficiency?
Heinz bodies
What type of anaemia can methotrexate cause?
Megaloblastic macrocytic anaemia 2ary to folate deficiency
What should be corrected before prescribing erythropoiesis-stimulating agents (ESA)?
Correct any iron deficiency
What can trigger an aplastic crisis in hereditary spherocytosis?
Parvovirus B19 infection
Why is calcium low in CKD?
Kidneys cannot activate vitamin D
What is pellagra?
Deficiency of vitamin B3 (niacin)
What features are seen in pellagra?
1) dermatitis
2) diarrhoea
3) dementia/delusions
1st line mx of autoimmune haemolytic anaemia?
Steroids
What condition are bite cells & blister cells on a blood film seen in?
G6PD deficiency
What is haptoglobin?
Produced by the liver.
1ary function is to bind free Hb.
Haptoglobin level in haemolysis?
LOW (as bound to free Hb)
What type of anaemia can anti-TB meds cause?
Sideroblastic anaemia
