Microcytic Anaemias Flashcards
Basic cause of microcytic anaemias?
Lacking a building block for Hb synthesis, cells continue dividing anyway because other parts fine so cells are small and contain little Hb
What does it mean when RBCs are hypochromic?
It means they’re lacking in colour because they contain little Hb
Microcytic anaemias are caused by a cytoplasmic or nuclear defect?
Cytoplasmic
Deficiency of which substances can cause hypochromic microcytic anaemias? (2)
Haem deficiency or globin deficiency
Haem deficiency caused by? (2) Which is most common?
lack of iron for erythropoiesis (most common),
or,
problems with porphyrin synthesis
Haem deficiency can be caused by lack of iron for erythropoeisis or by problems with porphyrin synthesis. Give two states in which iron is lacking?
iron deficiency (low body iron),
or,
anaemia of chronic disease - normal body iron but lack of available iron
Most anaemia of chronic disease is microcytic/normocytic/macrocytic?
normocytic
Problems with porphyrin synthesis is rare. List two causes of problems with porphyrin synthesis?
lead poisoning,
or,
congenital sideroblastic anaemias
Cause of globin deficiency?
thalassaemia
TAILS - causes of hypochromic microcytic anaemias
Thalassaemia, Anaemia of chronic disease, Iron deficiency, Lead poisoning, Sideroblastic anaemia
Top 3 most common causes of microcytic anaemia?
- iron deficiency,
- thalassaemia,
- Anaemia of chronic disease (but usually normocytic)
Where is most of our iron from order of most of iron to least?(6)
In red cell haemoglobin, (2500mg), macrophage stores, (500mg), parenchymal tissues e.g. liver stores, (500mg), erythroid marrow, (150mg), plasma (4mg), absorption (1mg/day)
We can absorb a lot of iron from our dietary intake. T/F?
False - can only absorb a small amount of iron
Iron turnover in plasma pool is very fast/slow?
Fast - 4mg in pool and move 20mg/day
Circulating iron is bound to ?
transferrin
Iron is stored in _____ mainly in the ____.
stored in ferritin mainly in the liver
Functions of iron? (2)
oxygen transport (Hb and myoglobin), electron transport (mitochondrial production of ATP)
How do you test functional iron?
Haemoglobin
How do you test transported iron? (3)
Serum iron,
Transferrin,
transferrin saturation
How do you test storage iron?
Serum ferritin
How many binding sites does transferrin, the protein, have for iron?
2
Where does transferring transport iron from and to?
from donor tissues e.g. macrophages, intestinal cells and hepatocytes to tissue expressing transferring receptors (especially erythroid marrow)
What does % saturation of transferrin with iron measure?
Iron supply
In what 2 instances is %saturation of transferrin with iron reduced?
iron deficiency,
anaemia of chronic disease
In what instance is % saturation of transferrin with iron increased?
Genetic haemachromatosis
Ferritin is a large intracellular protein and can store up to ____ ferric ions?
4000
There is a tiny amount of ferritin present in serum and it reflects intracellular ferritin synthesis in response to iron status of the host. Low ferritin means
Iron deficiency
How is iron deficiency confirmed?
Combo of anaemia and reduced storage iron i.e. decreased functional iron and low serum ferritin
What are 3 basic causes of iron deficiency?
not getting sufficient dietary iron,
losing iron,
malabsorption
What are two types of iron deficiency due to insufficient dietary intake?
absolute deficiency (rare in UK, usually veggie diets with other issues), relative deficiency more common especially in children and women of child bearing age
What are 3 examples of causes of iron deficiency due to blood loss?
Usually gastrointestinal e.g. tumours, ulcers, NSAIDS
menorrhagia,
haematuria
What are 2 causes of malabsorption of iron? (relatively uncommon)
coeliac disease,
achlorhydria
How can menstrual blood loss lead to iron deficiency?
Average blood loss is 30-40ml/month which is equivalent to 15-20mg iron/month. average daily intake 1mg/day so if heavy menstrual blood loss e.g. >60ml that means >30mg iron loss/month
List 4 sequential consequences of negative iron balance
- ferritin falls because stores exhausted,
- MCV falls because iron deficient erythropoiesis,
- Microcytic anaemia develops (may be relative),
- epithelial changes
List 3 epithelial changes of low iron
skin,
koilonychia,
angular chelitis
Iron deficiency is a diagnosis. T/F?
FALSE - symptom not diagnosis!! needs investigation
List 3 non-drug managements to improve iron intake
review diet - haem and non-haem iron,
improve gastric acidity,
review other medications e.g. anticoagulants, PPIs
If good supply of iron, how much can healthy bone marrow increase Hb concentration per week?
7-10g/L
Oral iron is best given on an empty/full stomach
empty
What is standard daily oral iron dose?
What dose may be sufficient?
100-200mg,
65mg may be sufficient
What are the 3 types of oral iron available in tablet form?
ferrous sulphate,
ferrous fumarte,
ferrous gluconate
What is the name of the liquid prep with lower iron concentration used in paeds?
Soium feredetate sytron)
Side effects of oral iron? (5)
constipation, nausea, vomiting, abdo pains, dark stools
When should you consider IV iron?
Only when oral unsuccessful due to poor tolerance,
poor compliance,
malabsorption (rare)
How are IV iron doses calculated?
based on degree of anaemia and patient weight
With both oral and IV iron, how long after starting treatment should you assess response?
4-6 weeks
If poor response to iron therapy, what are potential causes? which is most common and which is least common?
poor compliance (most common),
iron intake not matching loss,
ongoing blood loss,
malabsorption (rare)
In cases of poor compliance with iron therapy due to side effects, what is clinical management?
reduce frequency,
or
switch to lower iron containing prep,
or consider IV route
What should rise on FBC if good response to iron therapy? (3)
Hb,
MCV,
Reticulocyte count
How long do you typically need to continue iron therapy for stores to be replenished?
2-3 months
IV iron has a significantly better and faster response than well tolerated oral iron. T/F?
False - not necessarily better/faster
Which iron is found in plants and which in meat and which are we designed to absorb more readily?
Ferric in plants, ferrous in meat, designed to absorb ferrous more easily
Why are pernicious anaemia patients jaundiced?
ineffective erythropoiesis sp destruction in bone marrow, Hb leftover and forms bilirubin
