Iron Deficiency Flashcards
What are some iron containing proteins in the body?
- Hb
- Myoglobin
- Catalase
- cytochrome p450
- cycle-oxygenase
- cytochrome a,b,c
- ribonucleotide reductase
- succinate dehydrogenase
Where is most of the body’s iron?
In haemoglobin
-> most crucial consequences of iron def are seen in the blood and also: you become iron deficient before you become anemic
In what part of Hb is iron?
It is in the haem component and carries oxygen
Hb = 4 globin chains and one haem group
How much iron do you need in a day to re-make huge numbers of RBCs on a daily basis?
20mg/day but fortunately Iron is recycled -> we only need a fraction of that through digestion.
How much iron do men and women need every day?
Men - 1mg
Women - 2mg
-> loss through desquamated cells of skin and gut as well as menstruation
(generally 12-15mg in human diet every day)
Where is iron found
- Meat and fish(haem iron)
- Vegetables
- Whole grain cereal
- chocolate
-> one of the most abundant chemicals in food.
In what state can we absorb Fe?
Fe2+
How can beverages alter the form iron is consumed in?
- orange juice: you are more likely to absorb iron in the Fe2+ form
- tea : you are more likely to absorb iron in the Fe3+ form.
What are the factors that affect iron absorption?
DIET: - increase in haem iron - ferrous iron INTESTINE: - acid (duodenum) - ligand (meat) SYSTEMIC: - iron deficiency - anaemia/hypoxia - pregnancy
If you are pregnant or iron deficientt you will absorb more iron.
How is iron absorbed?
- in the enterocytes
- first duodenal cytochrome B transforms Fe3+ into Fe2+
- Fe2+ can enter the cells via DMT-1 (divalent metal transporter)
- Fe is eatery stored as ferritin inside the cell (first converted to Fe3+) or exit the cell into the blood via Ferroportin.
- Hepcidin inhibits ferroportin and therefore decreases the amount of iron that goes into the blood
- Iron transported in blood as transferrin by binding to apoferritin
High iron -> ? hepcidin - ?FP -> ? absorption
High iron -> high hepcidin - low FP -> low absorption
How much transferrin Is usually saturated with Fe?
50%
What 3 transferrin values might labs measure?
- Transferrin
- Total iron binding capacity, TIBC
- Transferrin saturation
What does erythropoietin cause?
- survival
- growth
- differentiation
What causes increase in erythropoietin?
Anemia -> hypoxia -> increase in erythropoietin _> RBC precursors
What is ACD?
- Anemia in ill patients
- there is no obvious cause except that the patient is ill.
Laboratory signs of being ill
- high CRP -> infection
- ESR increased
- Acute phase response: increases in the following
- ferritin
- FVIII
- fibrinogen
- immunoglobulins
What are some conditions associated with ACD?
- Chronic infections e.g. TB/HIV
- Chronic inflammation e.g. RhA/SLE
- Malignancy
- Miscellaneous e.g. cardiac failure
What is the pathogenesis of ACD?
- cytokine release -> cytokines prevent the usual flow of iron from the duodenum, to red cells.
What specifically do cytokines do in ACD?
- Stop erythropoietin increasing
- Stop iron flowing out of cells
- Increase production of ferritin
- Increase death of red cells
Therefore:- make less red cells
- more red cells die
- less availability of iron (stuck in cells/ferritin)
- include TNF-alpha and interleukins
What are some causes of iron deficiency?
- BLEEDING (e.g. GI or menstrual)
- increased use e.g. growth/pregnancy
- dietary deficiency e.g. vegetarians
- malabsorption e.g. coeliac
When would you do full GI investigations in a patient with iron disease?
- no coeliac antibodies
- good diet
- male
- women over 40
- post menopausal women
- women with scanty menstrual loss
What are full GI investigations?
- Upper GI endoscopy - oesophagus, stomach, duodenum
- Take duodenal biopsy
- Colonoscopy
- IF FIND NOTHING
- small bowel meal and follow through
What aside from GI investigations can be checked in patients with iron deficiency?
- Menstruating woman <40 ….if heavy periods OR multiple pregnancies and no GI symptoms do nothing
- ? Urinary blood loss
- Antibodies for coeliac disease
any bleeding will gradually decrease iron stores.
