Iron Deficiency Anaemia Flashcards
What is aetiology of iron deficiency anaemia?
- Pre-existing nutritional deficiency
- Underlying comorbidities (e.g. cancer)
- Anaemia of inflammation
- Blood loss from surgery
- Reduced absorption (bariatric surgery, coeliac disease, gastritis, drugs (PPIs)
- Reduced intake - eating disorders, vegan diet
- Increased requirements - infants, adolescents, athletes, pregnancy, blood donors
- Chronic blood loss - GI tumors, hook worm infestation, abnormal uterine bleeding
What is the composition of a RBC?
Each mature RBC contains 280 molecules of Hb
Each of the four globin subunits contains one iron atom in haem
Total body iron content is 3-4g
What is the role of Hepcidin?
Hepcidin is produced in the liver
Systemic iron homeostasis is finely regulated by hepcidin
Hepcidin blocks release of iron from macrophages and duodenal enterocytes and subsequently reduces iron availability.
Hepcidin blocks dietary iron absorption and iron recycling through macrophages
Genetic loss of hepidin results in iron overload disorders such as HH and Thalassaemia syndromes.
What is the role of Ferroportin?
Ferroportin is the only known mammalian iron export protein
It mediates dietary absorption and recycling of iron.
Which inflammatory cytokines are responsible for anaemia during an inflammatory response?
Cytokines IL-1, IL-6, IL-10 ad TNF-alpha promote iron sequestration into macrophages via transferrin.
IL-6 upregulated hepcidin which blocks duodenal iron absorption and causes iron retention in macrophages (hepcidin block)
Inflammation also reduced production of erythropoeitin
What is function of iron?
Iron is essential for:
1. Haemoglobin synthesis
2. Cell growth and differentiation
3. Neurotransmission
4. Host defence
5. Cardiopulmonary function
What is anaemia?
Hb < 130 g/L for both sexes
What investigations would you do to determine cause of IDA?
- Hb
- Ferritin
- CRP to interpret Ferritin result
- Transferrin saturation
What is Transferrin saturation?
TSat is a marker of the amount of iron bound to transferrin and reticulocyte haemoglobin content.
It is a measure of the amount of iron available for Hb production in the bone marrow.
What are the risks of preoperative anaemia?
Increased risk of:
1. Blood transfusion
2. In-hospital complications
3. Delayed hospital discharge
4. Poor recovery
5. Death or disability at 90 days post op
6. Unplanned ICU admission
What is the benefit of treating IDA in cardiac surgery?
In patients with impaired LV function, treating iron deficiency with IV iron with CCF improves functional status and reduces cardiovascular related hospital readmissions and mortality.
What are the risks of IDA in pregnancy?
IDA in pregnancy results from an imbalance between supply and demand.
Maternal anaemia is an risk factor for:
1. Preterm labour
2. SGA babies
3. Low birth weight
4. Increased foetal and neonatal mortality
5. Obstetric haemorrhage
What are the advantages and disadvantages of enteral iron?
Oral iron (Ferrous fumarate or ferrous sulphate) is:
1.Cheap
Disadvantages:
1. Low bioavailability
2. Causes constipation
3. Takes several months to correct
Once a day or alternate day dosing may be better absorbed and tolerated compared with traditional higher doses.
e.g. 40-60mg iron per day or 80-100mg on alternated days.
What is Sucrosomial iron?
Surcrosomial iron contains ferric pyrophosphate, which is protected by a phospholipid bilayer membrane.
The complex protects iron from the hepcidin-ferroportin pathways and can be tolerated in higher doses.
What are the advantages of IV iron?
- IV iron can bypass the ‘hepcidin block’ caused by inflammation and replenish intracellular iron stores
- Works quickly - 50% effective at 3 days, 75% at 2 weeks and max response at 4 weeks.
- Improvements in Hb concentrations, functional performance and QOL