9: Iron deficiency Flashcards
Explain the role of iron in erythropoiesis
Recall dietary sources of iron, absorption of iron, and causes of iron deficiency
Explain the clinical and haematological features
Recall diagnosis and management of iron deficiency
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What is the role of iron in erythropoiesis?
Binds oxygen inside Hb
Low iron = low Hb = anaemia
How do we lose iron everyday?
Shedding of desquamated cells of skin/gut
Bleeding (menstruation)
How much iron do we need a day?
Men = 1mg Women = 2mg
How much iron does human diet have?
12-15mg/day
Sources of iron in natural foods?
Meat/fish
Veg
Whole grain cereal
Absorption of iron in food?
Most iron NOT absorped
Ferrous iron Fe2+ is absorbed but NOT ferric iron Fe3+
Factors affecting absorption?
Diet: Increase in haem/ferrous iron
Intestine: acids, ligands
Sytemic: Iron deficiency, anaemia/hypoxia, pregnancy
How does gut cell affect iron absorption?
High iron -> High hepcidin (from liver) -> breaks down ferroportin -> less iron absorption into blood
Iron also has an intracellular form FERRITIN
Iron in plasma binds to TRANSFERRIN
Transferrin/Transferrin saturation are easy to measure in lab
How does EPO affect iron?
Anaemia -> tissue hypoxia -> increased EPO -> growth/survival/differentiation of red cells
What is anaemia of chronic disease (ACD)?
Anaemia in patients who are ill, no other cause (like bleeding)
Lab signs of being ill?
- C-reactive protein (mark of inflammation in ill patients)
- Erythrocyte sedimentation rate
- Increase in ferritin, factor 8, fibrinogen, immunoglobulins
Common causes of ACD?
- Chronic infection (HIV/TB)
- Chronic inflammation (Rh Arthritis, lupus)
- Malignancy
- other (e.g. cardiac failure)
Pathogenesis of ACD?
Due to release of cytokines which PREVENT the usual flow of iron from duodenum into red cells (i.e. stuck inside cells in form of ferritin)
Examples of cytokines?
TNF-a
Interleukins
Causes of iron deficiency? Give examples
- Bleeding (e.g. menstrual, GI)
- Increased use of iron (growth/pregnancy)
- Dietary deficiency (e.g. vegetarians)
- Malabsorption (e.g. coeliac disease)
What investigations do you take for iron deficiency?
FULL GI investigation if good diet and no coeliac antibodies, post-menopausal women, or men of any age
Need to check for cancer (e.g. renal cancer - might be bleeding in urine)
What is a full GI investigation?
Upper GI endoscopy Duodenal biopsy Colonoscopy Anti-coeliac/helicobacter antibodies Possibly ultrasound kidneys?
Lab parameters of iron deficiency?
- MCV
- Serum iron
- Ferritin
- Transferrin = total iron binding capacity
- Transferrin saturation
3 causes of low MCV?
- Iron deficiency
- Thalassaemia trait (heterozygous)
- ACD
If serum iron is low what could it mean?
Iron deficiency OR ACD
How do you confirm thalassaemia trait?
Haemoglobin eletrophoresis
Detects Hb variants in blood
Ferritin levels in chronic disease and iron deficiency?
LOW ferritin in iron deficiency
HIGH/normal ferritin in ACD
Transferrin levels in ACD/iron deficiency?
HIGHER transferrin in iron deficiency
NORMAL/LOW in ACD
Transferrin saturation in ACD/iron deficiency?
LOW in iron deficiency
NORMAL in ACD
What do you do after diagnosis of iron deficiency?
Full GI investigation
Men and iron deficiency?
Man of ANY AGE with LOW ferritin = IRON DEFICIENCY
Needs upper/lower GI endoscopies to find source of bleeding
Lab findings of thalassaemia trait?
Low Hb
Low MCV
Everything else normal
Lab findings of chronic disease (RhA) AND bleeding ulcer?
All LOW except Ferritin normal (should be high due to chronic disease) Transferrin low/normal
What is a last-resort mode of investigation you can do?
Give iron, see if anaemia gets better
