Haematology: Anaemia (Macrocytic; Pernicious & Haemolytic) Flashcards
What are specific signs associated with anaemia of vit. B12 deficiency? [1]
Glossitis
Define what is meant by pernicious anaemia [2]
Pernicious anaemia is an autoimmune condition involving antibodies against the parietal cells or intrinsic factor. Intrinsic factor is essential for B12 absoprtion
Specifically have:
- Antibodies to intrinsic factor: block vitamin B12 binding site
- Antibodies to gastric parietal cells: reduced acid production and atrophic gastritis. Therefore less B12 absorption
Where is B12 absorped? [1]
Distal ileum
Name two core uses of Vitamin B12 [2]
vitamin B12 is important in both the production of blood cells and the myelination of nerves → megaloblastic anaemia and neuropathy
Describe the clinical features of pernicious anaemia
Peripheral neuropathy, with numbness or paraesthesia (pins and needles)
**Loss of vibration sense **
Loss of proprioception
Visual changes
Mood and cognitive changes
TOM TIP: For your exams, remember to test for vitamin B12 deficiency and pernicious anaemia in patients presenting with []
TOM TIP: For your exams, remember to test for vitamin B12 deficiency and pernicious anaemia in patients presenting with peripheral neuropathy, particularly with pins and needles.
Describe the treatment regime for pernicious anaemia
Intramuscular hydroxocobalamin is initially given to all patients with B12 deficiency, depending on symptoms:
No neurological symptoms
- 3 times weekly for two weeks
Neurological symptoms
- alternate days until there is no further improvement in symptoms
MAINTENANCE:
Pernicious anaemia
– 2-3 monthly injections for life of intramuscular hydroxocobalamin
Diet-related:
- oral cyanocobalamin or twice-yearly injections
Describe why treating B12 deficiency before a folate deficiency is essential [1]
Where there is B12 and folate deficiency together, it is essential to treat the B12 deficiency first before correcting the folate deficiency.
Giving patients folic acid when they have a B12 deficiency can lead to subacute combined degeneration of the cord, with demyelination in the spinal cord and severe neurological problems.
Describe the presentation of subacute combined degeneration of the spinal cord [3]
progressive weakness
ataxia
paresthesias that may progress to spasticity and paraplegia
How would a B12 deficiency appear on a blood film? [1]
hypersegmented neutrophils on blood film
Pernicious anaemia has an increased risk of which cancer? [1]
Gastric cancer
Which vitamin is folate? [1]
B9
Describe causes of folate deficiency [6]
- Inadequate dietary intake
- Alcohol excess
- Malabsorption (e.g. coeliac disease, Crohn’s disease)
- Increased requirements (e.g. pregnancy, malignancy)
- Increased loss (e.g. Chronic liver disease)
- Other (e.g. anti-convulsants, ETOH abuse)
Why is folate an essential part of diet? [1]
THF plays a key role in the transfer of 1-carbon units (e.g. methyl, methylene, and formyl groups) to the essential substrates involved in the synthesis of DNA & RNA
Which investigations are used to diagnose folate deficiency? [1]
Red cell folate is a better measure of levels than serum folate, since levels are affected even with a short period of deficiency.
How do you treat folate deficiency? [1]
**Folic acid **is usually given as a **once daily oral dose of 5 mg for up to four months. **
[] is the most common cause of a non-megaloblastic anaemia
Explain your answer [1]
Chronic alcohol use is the most common cause of a non-megaloblastic anaemia.
It is thought to be due to the toxic effects of acetaldehyde on erythrocyte progenitors.
What advice should you give pregnant women regarding folic acid intake? [1]
Folate deficiency causes an increased risk of which pathology? [1]
all women should take 400mcg of folic acid until the 12th week of pregnancy
Risk of neural tube defects
Which heridatory diseases fall under umbrella of haemolytic anaemia? [5]
- Hereditary spherocytosis
- Hereditary elliptocytosis
- Thalassaemia
- Sickle cell anaemia
- G6PD deficiency
What are the subdivisions of hereditary haemolytic anaemias? [3]
Hereditary causes:
membrane:
* hereditary spherocytosis/elliptocytosis
metabolism:
- G6PD deficiency
haemoglobinopathies:
- sickle cell
- thalassaemia
What are the subdivisions of acquired haemolytic anaemias? [2]
Acquired: immune causes
autoimmune
-: warm/cold antibody type
alloimmune:
- transfusion reaction
- haemolytic disease newborn
drugs:
- methyldopa
- penicillin
Acquired: non-immune causes
microangiopathic haemolytic anaemia (MAHA):
- TTP/HUS
- DIC,
- malignanc
- pre-eclampsia
prosthetic cardiac valves
paroxysmal nocturnal haemoglobinuria
infections:
- malaria
drug:
- dapsone
What are the classical features of haemolytic anaemia? [3]
The features are a result of the destruction of red blood cells:
* Anaemia
* Splenomegaly (the spleen becomes filled with destroyed red blood cells)
* Jaundice (bilirubin is released during the destruction of red blood cells)
What are the key investigation results for haemolytic anaemia? [3]
Full blood count shows a normocytic anaemia
Blood film shows
schistocytes (fragments of red blood cells)
Direct Coombs test is positive in autoimmune haemolytic anaemia (not in other types)
Define what is meant by: [3]
- Hereditary spherocytosis
- Hereditary elliptocytosis
Hereditary spherocytosis
- Autosomal dominant familial condition; autoantibodies produced against proteins in RBC membrane mean it causes a spherical shape when they pass through the spleen
- Can still perform adequately despite reduced SA
- Fragile and easily lysed
Hereditary elliptocytosis:
- Autosomal dominant familial condition; autoantibodies produced against proteins in RBC membrane mean it causes an ellipse shape
- Can still perform adequately despite reduced SA
- Fragile and easily lysed
Describe a patient with hereditary spherocytosis may present [4]
- Jaundice at birth
- However the onset of jaundice can be delayed for many years and some
patients may go through life with no symptoms and are detected only during
family studies - May eventually develop anaemia
- Splenomegaly
- Ulcers on the leg
- Chronic haemolysis leads to the formation of gall stones
What investigations would indicate either hereditary spherocytosis or hereditary elliptocytosis? [3]
- Raised mean corpuscular haemoglobin concentration (MCHC) on a full blood count
- Raised reticulocyte count due to rapid turnover of red blood cells
- Spherocytes / elpitocytes on a blood film
What is the treatment of hereditary spherocytosis or hereditary elliptocytosis? [4]
Folate supplementation
blood transfusions when required
Splenectomy.
Gallbladder removal (cholecystectomy) may be required if gallstones are a problem.
Describe the pathophysiology of G6PD deficiency [1]
G6PD deficiency is caused by a defect in the gene coding for glucose-6-phosphate dehydrogenase (G6PD)
G6PD is responsible for protecting the cells from oxidative damage
Causes acute bouts of haemolytic anaemia
Describe the presentation of G6PD deficiency patients [2]
Most are asymptomatic but may get oxidative crisis due to reduction in
glutathione production
In attacks:
* Rapid anaemia
* Jaundice
Which drugs can trigger acute bouts of haemolytic anaemia in G6PD deficiency? [5]
Acute drug-induced haemolysis (dose-related):
- Aspirin
- Antimalarials such as; Primaquine, Quinine & Chloroquine
-
Antibacterials such as; Most Sulphonamides, Nitrofurantoin and
Chloramphenicol - Dapsone
- Quinidine
- Sulfonylureas
Fava beans.
Which drugs can trigger haemolytic anaemia in G6PD deficiency? [3]
Drugs:
- ciprofloxacin
- sulfonylureas
- sulfasalazine
What is the inheritance of G6PD deficiency? [1]
It is an X-linked recessive genetic condition
Describe the presentation of G6PD deficiency [4]
How can you diagnose this pathology? [1]
G6PD deficiency presents with:
- jaundice (often in the neonatal period)
- gallstones
- anaemia
- splenomegaly
- Heinz bodies on a blood film.
Diagnosis can be made by doing a G6PD enzyme assay.
Treatment for which pathology often triggers haemolytic anaemia in G6PD deficent patients? [1]
anti-malarials
Why might haemolytic present as macrocytic anaemia [as opposed to the normal presentation of normocytic]? [1]
if there are **many young RBC’s **(which are
larger) due to excessive destruction of old RBCs
Describe what is meant by the term a compensated haemolytic disease [1]
If the red cell loss can be contained within the marrow’s capacity for
increased output, then a haemolytic state can exist without anaemia
The bone marrow can increase its output by 6-8 times by increasing the
proportion of cells committed to erythropoiesis (RBC production) (erythroid
hyperplasia) and by expanding the volume of active marrow
Describe how you would treat a patient with hereditary spherocytosis in:
- neonates [2]
- infants (>28 days old), children, and adults [5]
Neonates:
- 1st line: supportive care +/- red blood cell transfusions
- 2nd line: folic acid supplementation
infants (>28 days old), children, and adults
- 1st line: supportive care +/- red blood cell transfusions
- 2nd line: folic acid supplementation
- 3rd line: splenectomy with pre-op vaccination regimen
- Consider: cholecystectomy or cholecystostomy
- Plus: post-splenectomy antibiotic pneumococcal prophylaxis
