haemoglobin 8: iron deficiency Flashcards
what are some examples of iron containing proteins?
haemoglobin, myoglobin, catalase, cytochrome P450, cytochrome a&b&c, succinate dehydrogenase, ribonucleotide reductase
what is the structure of haem?
protoporphyrin ring in the middle with a central Fe that binds to oxygen
why do we need dietary intake of iron?
although most iron is recycled some is lost from desqamated cells of skin & gut & menstruation
how much iron do we need each day?
men = 1mg, women = 2mg
what food sources provide iron?
meat & fish (good as iron already in haem)
vegetables
whole grain cereal
what form of iron can we absorb?
Fe2+ (cannot absorb ferric Fe3+)
what factors affect iron absorption?
- diet (eg consumption of haem iron / ferrous v ferric)
- intestine (eg acidity in duodenum)
- systemic (eg anaemia/hypoxia, pregnancy increases iron absorption)
how does iron enter plasma from duodenal cells?
via ferroportin
what regulates levels of ferroportin?
hepcidin (dependent on levels of iron)
what happens when hepcidin levels are high?
hepcidin high -> binds to ferroportin -> ferroportin cannot transport iron
what happens when iron is absorbed into plasma?
binds to transferrin (carrier protein)
what effect does anaemia have on RBC production?
anaemia -> tissue hypoxia -> increase in erythropoietin -> increase in red blood cell production - red cell precursors survive longer and grow + differentiate
what is ACD?
anaemia of chronic disease - anaemia in patients who are unwell
what are the laboratory signs of being ill?
- high c-reactive protein
- high erythrocyte sedimentation rate
- acute phase response -> increase in ferritin / FVIII / fibrinogen / immunoglobulins
what are some associated conditions of ACD?
- chronic infection eg TB, HIV,
- chronic inflammation eg RhA/SLE, malignancy,
- miscellaneous eg cardiac failure
what do cytokines do in relation to iron in the system?
prevent iron utilisation by:
- blocking usual flow of iron from duodenum to red cells
- stopping increase in erythropoietin
- increasing production of ferritin
what effects do cytokines therefore have?
- reduced production of red cells
- increased death of red cells
- less availability of iron
what are the causes of iron deficiency?
- bleeding (eg menstrual/GI),
- increased use (eg growth, pregnancy)
- dietary deficiency (eg vegetarian)
- malabsorption (eg coeliac)
when would you carry out a full GI investigation?
if good diet and no coeliac antibodies:
- male
- post-menopausal women
- women with light periods
what is a full GI investigation?
upper GI endoscopy (oesophagus, stomach, duodenum), colonoscopy, duodenal biopsy & if nothing found -> small bowel meal and follow through
what laboratory parameters can be measured to test for anaemia?
- MCV
- serum iron
- ferritin
- transferrin (=TIBC), transferrin saturation
what are the 3 common causes of low MCV?
- iron deficiency
- thalassaemia trait
- ACD (MCV could be low or normal)
how can ferritin levels distinguish between iron deficiency & ACD?
low in iron deficiency, high in ACD (ferritin is an acute phase protein)
how can transferrin levels distinguish between iron deficiency & ACD?
high in iron deficiency, normal/low in ACD
how can transferrin saturation distinguish between iron deficiency & ACD?
low in iron deficiency, normal in ACD
iron deficiency: Hb: MCV: Serum iron: Ferritin: Transferrin: Transferrin saturation:
Hb: LOW MCV: LOW Serum iron: LOW Ferritin: LOW Transferrin: HIGH Transferrin saturation: LOW
ACD: Hb: MCV: Serum iron: Ferritin: Transferrin: Transferrin saturation:
Hb: LOW MCV: LOW/NORMAL Serum iron: LOW Ferritin: HIGH/NORMAL Transferrin: NORMAL/LOW Transferrin saturation: NORMAL
Thalassaemia trait: Hb: MCV: Serum iron: Ferritin: Transferrin: Transferrin saturation:
Hb: LOW MCV: LOW Serum iron: NORMAL Ferritin: NORMAL Transferrin: NORMAL Transferrin saturation: NORMAL
what are the clinical features of iron deficiency?
- fatigue
- weakness
- pale skin
- lightheadedness
- shortness of breath
