Anaemia Flashcards
How many red blood cells are present in the body
24 trillion
What is total body iron mass
3-5g
Where is majority of dietary iron absorbed?
In the duodenum by enterocytes
In what forms can dietary iron be absorbed?
Fe2+
As part of a protein
How is Fe3+ reduced to Fe2+
Ferric reductase enzyme found on brush border of duodenum
What are transferrins
Iron binding blood plasma glycoproteins used to control levels of free iron in plasma
How many Fe3+ ions can a transferrin carry
2
Where does iron go once its been absorbed
Bone marrow
What takes up iron ions once inside the cell
Ferritin
How is iron stored
Why?
Inside cells in ferritin
Allows iron to be released in a controlled manner and is a buffer against deficiency or overload
What counts as anaemia for a male adult?
Hb less than or equal to 13.5g/dl
What counts as anaemia for female adult
Hb<11.5g/dl
What counts as anaemia for child 6m-6y?
Hb<11g/dl
What counts as anaemia for child 6-14y?
Hb<12g/dl
Symptoms of anaemia?
Tiredness Fainting Shortness of breath Worsening angina Rapid heart
Signs of anaemia
Pallor Rapid heart Bounding pulse Systolic flow murmur Cardiac failure
What can cause anaemia by causing decreased production of red cells (5)
- Iron deficiency
- B12/ folate deficiency
- Marrow infiltration
- Chronic disease
- Infection
What can cause anaemia by causing increased deustruction (haemolytic anaemia)
- Immune destruction
-Disorders of RBC
(haemolytic anaemia)
What are the MCV guidelines in terms of categorising anaemia?
Microcytic: MCV<76fl
Normocytic: MCV 76-96fl
Macrocytic: MCV>96fl
2 main causes of microcytic anaemia
Iron deficiency and thalassaemia
How do red blood cells appear in iron deficiency anaemia?
Small/ microcytic
Hypochromic
Presence of pencil cells
Risk factors for iron deficiency anaemia
Age (premature/ elderly)
Sex (F>M)
GI (appetitte/ weight changes)
Drugs (aspirin/ NSAIDS)
What is the worldwide most common cause of iron deficiency anaemia
Hookwormm
4 most common causes of iron deficiency anaemia in the developed world
Reproductive (eg menorrhagia)
GI tract bleeding (ulcers, IB, cancers)
GI tract malabsorption (coeliac, atrophic gastris_
Vegan
What woulld full blood count show in iron deficieny anaemia
Low RBC
Main causes of normocytic anaemia
Acute blood loss Chronic disease Cancer Haemolysis Metastatic cancer (marrow infilitration)
How does chronic disease lead to normocytic anaemia
- Causes reduced red blood cell lifespace leading to depressed erythropoiesis
- Poor marrow response to EPO as inflammatory cytokines interfere with EPO production/ action
Another name for vitamin B12?
Cobalmin
Funtions of vitamin B12?
Synthesis of myelin and assists in DNA synthesis
Involved in metabolism of every cell- especially cells with high turnover
Result of prolonged vitamin B12 deficiency?
Severe and irreversible nerous system daamge
Is vitamin B12 destroyed by cooking?
No
How much B12 is required? How much is stored
1mg/d
1000mg
Where is B12 absorbed
Ileum
What is another name for vitamin B9?
Folate
What types of food is B9 found in?
Liver, greens, yeast
Is B9 destroyed by cooking
Yes
How much B9 is required
150mg/d
How long is B9 stored for
4 months
Where is B9 absorbed?
Duodenum and jejunum
What difficulties are presenting in diagnosing B12/ B9 deficiency
They are clinically indistinguishable from each other
What type of anaemia to B12/ B9 deficiencies lead to
Macrocytic anaemia
How can B12 deficiency be detected?
Measured clinically as increased serum methylmalonic acid
To what extent can eating more B9 cure/ solve B12 deficiency?
Lack of DNA synthesis can be solved by folate, but the reduced myelin synthesis cannot be
Describe how B9/12 deficienies lead to macrocytic anaemia
- Both required for DNA synthesis
- Reduced/ impaired DNA synthesis
- Cells fail to divide
- Overlarge blood cells
Where is intrinsic factor produced
Produced by parietal cells in the gastric mucosa
Describe absorption of vitamin B12?
Absorbed by body by ileum after binding to intrinsic factor. Intrinsic factor- B12 complex absorbed by receptors on ileum endothelial cell
Where is vitamin B12 released from the protein its bound to?
In stomach by acid
What would the blood count of a person with B12/B9 deficiency show?
Low Hb
High MCV>120
Low WBC and platelets
What would the blood film of a person with B12/B9 deficiency show?
Oval macrocytes
Hypersegmented neutrophils
What would biochem tests of a person with B12/B9 deficiency show?
High bilirubin
High lactate dehydrogenase
How is pernicious anaemia characterised?
B12 deficiency caused by absence or reduction of intrinsic factor
Autoimmune disorder
Occurs due to an antibody against gastric mucosa and intrinsic factor
Who does pernicious anaemia most commonly effect?
Females with fair hair, blue eyes and group A blood
Symptoms of pernicious anaemia
- Glossitis
- Mild jaundice
- Dementia
- Peripheral neuropathy
- Optic atrophy
- Insididious
How is pernicious anaemia treated?
Every 3 months you have an IM B12 injection for life
How do symptoms of B12 and B9 differ
All same symptoms, but folate deficiency gives no neurological symptoms
How is folate deficiency treated
Oral folate tablets
Examples of intravascular haemolysis
Sickle cell
Thalassaemia
Rhesus mismatch
Hereditary spherocytosis
Examples in extravascular haemolysis
ABO mismatch
Snake bites
Infection
How does haemolytic anaemia present
Pallour and anaemia
Jaundice
Gall stones
Splenomegaly
What will lab investigations show for somebody with haemolytic anaemia?
- Red cell breakdown: increased serum unconjugated bilirubin, increased urinary urobilogen, increased lactate dehydrogenase.
- Increased RBC production: increased reticulocytes, increased RBCs in marrow
3 types of haemolytic anaemia
1) Membrane defect
2) Haemoglobin defect
3) Enzyme defect
Define spheryocyte
Sphere shaped RBC
What type of haemolytic anaemia results from hereditary spherocytes?
Membrane defect
What causes hereditary spherocytosis
Defect in protein of red cell cytoskeleton.
Blood cells contracts to its most surface tension efficient/ most flexible form (sphere)
Are spherocytes more or less fragile than normal RBC?
More fragile (could break when passing through capillaries)
What is the result of increased fragility of spherocytes?
Break down more- chronic haemolytic anaemia.
Low Hb, high LDH, high unconjugated serum bilirubin
What is the inheritance pattern of hereditary spherocytosis
Autosomal dominant
Example of haemolytic anaemia due to an enzyme defect
G6PD deficiency
What is the role of G6PD?
Prevents/ reverses haemoglobin oxidation
Inheritance pattern of G6PD deficiency
X linked
3 main triggers of G6PD deficiency?
Foods (fava beans)
Bacterial/ viral
Drugs
Approx how much iron is in 1ml of blood
0.5mg
How much blood loss/ day will result in iron deficiency
10ml loss/ day
What 6 things can enhance absorption of iron
- Haem iron
- Ferrous salts
- acidic pH
- Iron deficiency
- Pregnancy
- Hypoxia
What 5 things can impair the absorption of iron
- Non-haem iron
- Ferric salts
- Alkaline pH
- Iron overload
- Inflammatory disorders
Name a drug type that can decrease iron absorption
Proton pump inhibitors (indigestion)
What disorder of the haematopoietic stem cells in bone marrow may lead to macrocytic anaemia
Myelodysplasia
What conversion reaction are b12 and folate needed for
Homocysteine–> methionine
What happens in autoimmune haemolytic anaemia
- IgG antibodies present in blood that react with RBC membrane proteins
- Affects RBC then removed my spleen–> extravascular haemolysis