Haem 9 - Iron deficiency Flashcards
List some compounds containing iron
Haemoglobin - most of the iron is in Hb Myoglobin Catalase Cytochrome P450 Ribonucleotide reductase Cyclo-oxygenase Cytochrome a,b,c Succinate dehydrogenase
What is the role of iron in Hb?
Holds onto oxygen. Ferrous iron sits in the centre of protoporphyrin ring.
low iron = low Hb = anaemia
What is the daily requirement of iron? Describe the absorption of iron.
20mg iron/day - fortunately iron is recycled
Human diet provides 12-15 mg iron/day in most foods: meat and fish (haem), vegetables and whole grain cereal. However most iron is not absorbed.
Only Fe2+ is absorbed.z
How is iron lost from the body?
1) Desquamated cells of skin and gut (shedding off of cells)
2) Bleeding - menstruation
To replace these losses in iron:
Men require: 1mg/day
Women require: 2mg/day
What are the factors that affect the absorption of iron?
DIET: increase in haem iron (red meat+fish)
- ferrous iron (you can absorb)
INTESTINE: acid (duodenum)
- ligand (meat)
SYSTEMIC: iron deficiency (you absorb more iron)
- anaemia/hypoxia
- pregnancy
How does the gut cell alter iron absorption?
Iron is transported across the basal side side of the cell by ferroportin. Ferroportin is regulated by hepcidin - high levels of hepcidin causes ferroportin to be internalised = decreased iron transport.
High iron –> High hepcidin –> Low ferroportin –> Low absorption
What forms can iron exist in?
Iron absorbed in the diet
Ferritin = intracellular iron
Iron is attached to transferrin = plasma iron
Describe transferrin
Binds to iron in the circulation:
Transferrin saturation
- usually 20-40% saturated with iron
- low iron would show low transferrin saturation
TIBC - Total Iron Binding Capacity
What are the three effects of erythropoietin?
Causes erythrocytes to:
- Survive
- Grow
- Differentiate
Define anaemia of chronic disease
ACD: Anaemia in patients who are unwell but there is no obvious cause except that they are ill
What are the laboratory signs that a patient is ill causing ACD?
C-reactive protein - mark of infection/inflammation
Erythrocyte Sedimentation Rate - ESR goes up in inflammation
Acute phase response- increases in
- ferritin
- FVIII
- fibrinogen
- immunoglobulins
What the common associated conditions of ACD?
Chronic infections e.g. TB/HIV
Chronic inflammation e.g. RhA/SLE
Malignancy
Miscellaneous e.g. cardiac failure
Describe the pathogenesis of ACD?
Cytokines released prevent the usual flow of iron from the duodenum to red cells - essentially blocks iron being utilised.
Examples of cytokines - TNF alpha and Interleukins
- 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)
What are the causes of iron deficiency?
- Bleeding e.g. menstrual/GI
- Increased use e.g. growth (puberty children growing quickly)/pregnancy (baby with take the iron first)
- Dietary deficiency e.g. vegetarian because they don’t get haem in meat and fish
- Malabsorption e.g. coeliac - affect absorption of iron
When are full GI investigations performed?
Iron deficiency is taken seriously if you are iron deficient and anaemic.
- Good diet and no coeliac antibodies…..
- Male
- Women over 40
- Post menopausal women
- Women with scanty menstrual loss
You want to exclude coeliac disease, colon cancer and gastric cancer - this is to ensure there is no GI bleeding.
Menstruating woman <40 ….if heavy periods OR multiple pregnancies and no GI symptoms do nothing. These are all reasons for why there is anaemia so you don’t need to look at the GI tract.
