Iron Flashcards
Where is the majority of iron in the body?
Haemoglobin and stored in ferretin
What are the two types of iron?
Ferric (Fe3+)- insoluble
Ferrous (Fe2+)- soluble
What is the total body iron content in an adult?
2-5g
Sources of haem iron
Red meat, pork, fish
Sources of non-haem iron
Nuts, eggs, beans
Average Western iron intake?
10-15mg
How much iron is absorbed and where?
5-10% absorbed through the duodenum
How is iron converted?
Converted from Fe3+ to Fe2+ by duodenal cytochrome b.
What inhibits iron absorption?
phytates, tannins (tea) and tetracycline (antibiotics)
What enhances iron absorption?
Vitamin C
How is iron lost?
Sweat, shedding of skin cells, faeces
How is iron absorption regulated?
Regulated according to the body’s needs by changing the levels of DMT-1. Levels of DMT-1 are increased in iron deficiency to increase absorbance.
How is iron transported across the basal membrane to the plasma and how is it controlled?
Ferroportin. A decrease in hepcidin increases ferroportin to allow more iron to enter the plasma.
What happens to the level of soluble transferrin receptors (sTFr) during iron deficiency anaemia?
It is increased.
Features of ferritin
- Water soluble
- Protein shell enclosing an iron core
- Serum ferritin most valuable diagnostic of iron status
- Easily measured by ELISA
Features of haemosiderin
- Water insoluble
- Derived from lysosomal digestion of ferritin aggregates.
- Found in macrophages
- Increased in iron overload
- Pappenheimer bodies (removed by spleen)
Normal values of: serum ferritin, transferrin and serum iron.
serum ferritin: 20-300ug/L
transferrin: 1.7-3.4g/L
serum iron: 10-30umol/L
What is the definition of anaemia?
Low level of haemoglobin in the blood
What are the WHO criteria for anaemia?
men: less than 13g/dL
women: less than 12g/dL
What are the causes of anaemia?
- Decreased red cell production
- Increased destruction of RBCs
- Blood loss- not apparent straight away because the total blood volume is reduced.
How is anaemia diagnosed?
- MCV measured
- Neutrophil and platelet counts rise when anaemia is caused by haemolytic or haemorrhage.
- Measurement of leucocytes and platelets distinguishes between pure and pancytopenia anaemias.
- Reticulocyte count should increase because of Epo increase. It remain raised until Hb levels return to normal.
What is the physiological response to anaemia?
Main goal is to maintain adequate oxygenation of the body. This is achieved by:
- 2,3-DPG level rise
- Cardiac output increase and circulation becomes hyper dynamic
- Inc. in stroke volume and tachycardia.
What are the symptoms of anaemia?
- Pale
- Fatigue
- Dyspnoea
- Palpitations
- Headache
What do symptoms of anaemia depend on?
- Speed of onset: faster=more symptoms
- Severity: mild usually causes no symptoms
- Age: worse in elderly
- Hb-O2 dissociation curve: shift to the right
What are the clinical signs and symptoms of iron deficiency anaemia?
- Flattening or spooning of the nails
- Angular stomatitis
- Glossitis
- Increased fatigue
What does the blood film show in iron deficiency anaemia?
- Hypochromic RBCs
- Microcytic RBCs
- Anisocytosis
- Poikilocytosis
Laboratory findings of iron deficiency anaemia
- Hb conc. decreases
- Mean cell volume <80fl
- Ferritin is low
- Hepcidin is decreased
- Rise in transferrin and less saturated
- Increase in amount of transferrin receptor
- Serum ferritin is v. low
How is iron deficiency anaemia treated?
Iron sulphate supplements- lasts for 6months
What happens if iron is accumulated?
Serious damage to heart, liver and endocrine organs.
What are the main causes of iron overload?
- Increased iron absorption
- Repeated blood transfusion
- Increased intake
What is a disorder characterised by excessive iron storage and what are the features?
Hereditary haemochromatosis
- Autosomal recessive condition
- Excessive absorption of iron from the GI tract
- High incidence in Northern Europeans
- Treatment= venesection
