Iron Deficiency Flashcards
(43 cards)
Where is Iron normally found?
Found in many PROTEINS
inc. myoglobin, catalase, cytochrome P450 etc.
BUT most iron found in Hb
Link between Iron and Hb?
Low Iron = Low Hb = anaemia
What is the role of Iron in Hb?
Iron (specifically FERROUS) found in the
HAEM part
of Hb and its role is to hold onto O2
Iron homeostasis?
RBCs live for ~120 days!
Need around 20mg iron/day to replace lost RBCs
BUT
we can recycle iron!
How can iron be lost in the body?
o Desquamated cells of skin & gut
o Menstruation (bleeding)
How much iron do men and women need?
Men = 1mg/day
Women = 2mg/day
Where can we get iron from but what is an issue of this?
- Human diet
o provides ~12-15mg/day
o e.g. meat & fish (haem iron), veg, chocolate, whole grain cereal
BUT
most iron eaten is NOT absorbed
o can NOT absorb ferric iron (Fe3+)
o can only absorb ferrous iron (Fe2+)
How can you tackle the problem with iron absorption from diet? What makes it worse?
Orange Juice AIDS absorption of iron
Cups of tea makes it WORSE
o turns iron into the FERRIC form
o can lead to chronically low levels of FERROUS!
Factors affecting absorption of Iron?
Diet
o increase in haem iron (ferrous iron)
Intestine o acid in the duodenum o ligand (meat)
Systemic
o Iron deficiency (anaemia/hypoxia, preganacy)
Factors that INCREASE iron absorption?
Iron deficiency
Anaemia/hypoxia
Pregnancy
How is iron absorbed in the gut?
- Iron freely transports into the cell from the gut lumen
- FERROPORTIN facilitates transport of iron into the blood
o HEPCIDIN inhibits ferroportin
Hepcidin is regulated
o has iron-responsive elements within their gene
o so iron part of complex that switches on its transcription
Ferroportin is found in
o enterocytes (dudodenum)
o macrophages (spleen)
o hepatocytes
How is Iron held onto in the circulation?
TRANSFERRIN!
- Iron taken into cells
- Protein shell forms around it
o forms FERRITIN micelles - Once iron enters plasma via. ferroportin, is linked to transferrin which transports it around the body
Characteristics of Transferrin and how it can be measured?
Usually 20-40% saturated with iron
o NEED it because iron is TOXIC & INSOLUBLE
o Transferrin levels
o Total Iron Binding Capacity (TIBC)
o Transferrin saturation
CAN all therefore be measured
Can TF enter cells directly?
NO
o bind with the TF-R and is internalised as a whole
As pH DROPS:
o iron is released
o TF-R are recycled
EPO?
Erythropoietin
Produced in kidneys
o production increased in response to hypoxia
o triggers more RBC precursors to be released
o the precursors survive longer and will survive, grow and differentiaite
ACD?
Anaemia of Chronic Disease
What is ACD?
Anaemia seen in patients who have a chronic disease
Cause of ACD?
Patient will NOT show classic causes of anaemia
i.e. bleeding
bone marrow infilitration
have a iron/B12 or folate deficiency
There is NO obvious cause
Laboratory signs of ACD?
- Higher levels of C-reactive protein (CRP)
o an acute phase protein (inflammation/infection) - Higher Erythrocyte Sedimentation Rate (ESR)
o rises in inflammation/infection - Acute phase response - increases in:
o Ferritin (usually reflects iron stores BUT is acutely ill levels shoot up as an acute phase protein so no longer good measure of iron during acute illness)
o F8
o Fibrinogen
o Igs (esp. IgG)
Conditions associated with ACD?
o Chronic infections e.g. TB/HIV
o Chronic inflammation
o Malignancy
o Miscellaneous e.g. cardiac failure
What normally causes the pathogenesis of ACD?
Due to CYTOKINE release
e.g. TNFalpha & ILs
How does this pathogenesis demonstate itself in ACD?
The cytokines:
o prevent usual flow of iron from dudodenum to RBCs
o stop EPO increasing
o stop iron flow out of cells
o increase ferritin production
o increase RBC death
SO makes less RBCs = more RBCs die = less iron available
Major cause of iron deficiency?
BLEEDING
e.g. menstrual OR GI
Minor causes of iron deficiency?
Increased use of iron
e.g. growth/pregnancy
Dietary deficiency
e.g. vegetarian
Malabsorption
e.g. coeliac
