Introduction to anaemia and microcytic anaemia Flashcards
What is anaemia?
Anaemia is present when there is a decrease in haemoglobin in blood below the reference level for the age and sex of the individual.
What is haematocrit?
Haematocrit measures the proportion of red blood cells in your blood.
What are the haemoglobin and haematocrit values in anaemia for adult males and females?
Adult males Hb <130g/L Hct <0.38
Adult females Hb <120g/L Hct <0.37
What is the normal response to anaemia?
To make more red cells (reticulocytosis)
Upregulation takes a few days
Reticulocytes: cells that have just left the bone marrow.
- Larger than average red cells
- Still have remnants of RNA - stain purple/deeper red, blood film appears “polychromatic”
Does decreased red cell production result in a low or high reticulocyte count and what are some causes?
Low reticulocyte count
Potential causes:
- Hypoproliferative - reduced amount of erythropoiesis
- Maturation abnormality - erythropoiesis present but ineffective
For maturation abnormality where erythropoiesis is present but ineffective, what are some of the potential causes?
Cytoplasmic defects - impaired haemoglobinisation
Nuclear defects - impaired cell division
Does increased loss or destruction of red cells result in a low or high reticulocyte count, what are some of the potential causes?
High reticulocyte count
Potential causes:
- Bleeding
- Haemolysis (rupturing/lysis of red blood cells)
What is the definition of a reticulocyte?
An immature red blood cell without a nucleus, having a granular or reticulated appearance when suitably stained.
What are the symptoms of anaemia?
The symptoms of anaemia are non - specific and include breathlessness, fatigue, headaches, palpitations and faintness.
What are the signs of anaemia?
- Pallor
- Tachycardia
- Systolic flow murmur
- Cardiac failure
Investigations for anaemia?
Bloods: full blood count
- Hb concentration, MCV, haematocrit, mean cell haemoglobin and mean cell haemoglobin concentration.
Blood film: look at cellular morphology
Reticulocyte count: assess marrow response
Additional tests - depending on clinical details and lab findings.
What is microcytic anaemia?
Anaemia caused by deficient haemoglobin synthesis (cytoplasmic defect)
What are the causes of microcytic anaemia?
Haem deficiency
Globin deficiency
What are the causes of haem deficiency in microcytic anaemia?
Lack of iron for erythropoiesis
- Iron deficiency - most common cause of microcytic anaemia
- Anaemia of chronic disease - IL-6 is released due to chronic diseases.
Problems with porphyrin synthesis
- Sideroblastic anaemia: excess iron build-up in mitochondria due to failure to incorporate iron into haem, can be hereditary (congenital sideroblastic anaemias) or acquired e.g. lead poisoning.
What are the causes of globin deficiency in microcytic anaemia?
Thalassaemia (trait, intermedia, major)
What are the causes of iron deficiency?
Insufficient intake to meet physiological need
- More likely in women and children due to greater requirements.
- Dietary factors
Losing too much - bleeding
- Causes of chronic blood loss: menorrhagia, GI (tumours, ulcers, NSAID’s, parasitic infection), haematuria.
Not absorbing enough - malabsorption e.g. coeliac disease (less common).
Summary of iron metabolic pathway?
‘Closed’ system - only able to absorb a small amount of iron
Tiny amount in circulation moving to/from storage site to being utilized – principally by marrow
Turnover in plasma pool is fast (4mg in pool and move 20mg/day)
Circulating iron is bound to transferrin.
It is transferred to the bone marrow macrophages that regulate iron uptake by transferrin receptor expression
They ‘feed’ iron to red cell precursors
Iron is stored in ferritin mainly in the liver
What is circulating iron bound to?
Transferrin
What available tests are used to assess iron status?
Functional iron
- Haemoglobin
Transported iron
- Serum iron
- Transferrin
- Transferrin saturation
Storage iron
- Serum ferritin
What is transferrin?
A protein with two binding sites for iron
Transports iron from donor tissues (macrophages, intestinal cells and hepatocytes) to tissues expressing transferrin receptors (especially erythroid marrow)
What can be used to measure iron supply?
% saturation of transferrin with iron is a measure of iron supply
- reduced in iron deficiency
- reduced in anaemia of chronic disease
- increased in genetic haemachromatosis
What is ferritin?
Large intracellular protein
Spherical protein stores up to 4000 ferric ions
Tiny amount of ferritin is present in serum
- reflects intracellular ferritin synthesis in response to iron status of the host
Can serum ferritin be easily measured?
Serum ferritin is easily measured but an indirect measure of storage iron.
What does a low ferritin indicate?
Iron deficiency
How can iron deficiency be confirmed?
Iron deficiency can be confirmed by a combination of anaemia (decreased functional iron) and reduced storage iron (low serum ferritin)
Iron deficiency anaemia is a diagnosis. True/false?
False
It is a symptom and is important to figure out underlying diagnosis.
Is it:
Diet
Malabsorption
Blood loss
If blood loss where/what from – could be occult malignancy
What are some ways to improve iron intake with iron deficiency anaemia?
Improve iron intake
- Review diet - haem and non haem iron
- Improve gastric acidity
- Vitamin C supplementation may benefit - facilitates absorption of iron
What forms can iron preparations be available in?
Oral and IV forms
What are the side effects of oral iron preparations?
Principally GI e.g. constipation, nausea + vomiting, abdominal pain, dark stools - can result in low compliance.
What are the side effects of IV iron preparations?
Only considered when oral is unsuccessful due to poor tolerance, poor compliance, malabsorption issues.
Used in specific situations such as renal anaemia
Why is it important to assess response for 4-6 weeks after period of iron treatment?
In order to identify for a potential cause if there is a poor treatment response
How long is iron treatment required in order to replenish stores?
2-3 months
Iron replacement therapy can treat the underlying problem. True/false?
False
Iron replacement therapy may relieve the symptom without treating the underlying problem - investigations essential to identify diagnosis e.g. early surgery for GI tumours may be curative.
