Iron deficiency

Question 1

What type of iron is absorbed?

Answer 1

Fe2+ not Fe3+

Question 2

How much iron do we need in our diets?

Answer 2

Men 1mg
Women 2mg

This is because we recycle the iron in our bodies and only need to replace the iron lost i.e. menstruation

Question 3

Describe iron absorption:

Answer 3

Fe 2+ into the cell and out of the cell by ferroportin which is regulated by hepcidin.

Low iron = high hepcidin which degrades the ferroportin and so less in the blood.

Ferritin in the cell and in the plasma it is transported with transferrin.

Question 4

What is the significance of transferrin?

Answer 4

You can measure the transferrin levels and saturation very easily and so this is easily tested in the lab.

Normal levels are 20-40% (low iron low transferrin)

Question 5

What is erythropoietin?

Answer 5

Made mainly in the kidneys - also in the liver.

If anaemic this is detected as a tissue hypoxia to stimulate erythropoietin - helps the red cell to grow.

Question 6

Anaemia of chronic disease vs iron deficiency anaemia:

Answer 6

Anaemia of chronic disease - in patients who are unwell (no known cause)

To check this:
-C-reactive protein (Sign of inflammation or infection)
-Erythrocyte sedimentation rate 
-Acute phase response - increases in:
>ferritin 
>FVIII
-Fibrinogen 
>immunoglobins

Common causes:
TB
HIV
Rheumatoid arthritis 
Cardiac failure 
Malignancy

Question 7

What is the significance of cytokines in chronic disease:

Answer 7

Cytokines do several things

1. Stop erythropoietin increasing
2. Stop iron flowing out of cells
3. Increase production of ferritin
4. Increase the death of red cells

Question 8

What is the main causes of iron deficiency:

Answer 8

Bleeding - periods or GIT

Dietary deficiency - meat and fish have a haem group which is easy to absorb iron from (harder to absorb from other foods as not haem group)

Malabsorption - coeliac

Increased use - growth and pregnancy

Question 9

Who would you investigate further with iron deficiency:

Answer 9

Male
Women over 40
Post-menopausal women
Women with scanty menstrual loss

For these people will have full GI investigations

Question 10

What are full GI investigations?

Answer 10

Upper GI endoscopy

Take duodenal biopsy

Colonoscopy

Question 11

What are the lab parameters to test for iron deficiency:

Answer 11

MCV - the average size of the RBC

Serum iron

Ferritin - storage protein (this is the gold standard for detecting iron deficiency as low in iron deficiency but high in chronic disease)

Transferrin - transfer protein (high in iron deficiency but low in chronic disease)

Transferrin saturation (low saturation with iron deficiency but normal in chronic disease)

Question 12

What are three causes of low MCV?

Answer 12

1. Iron deficiency
2. Thalassaemia trait
3. Anaemia of chronic disease (low or N) - serum iron is low

Question 13

What are issues with ferritin?

Answer 13

It can be normal but high CRP and ESR will indicate otherwise.

Question 14

What are the parameters of iron deficiency?

Answer 14

Hb					LOW
MCV			        LOW
Serum iron 			LOW
Ferritin 				LOW
*Transferrin 			HIGH
Transferrin saturation 	LOW

On a film - the pencil cell is diagnostic of this

Question 15

What are the parameters of chronic disease anaemia?

Answer 15

Hb					LOW
MCV				LOW or NORMAL
Serum iron 			LOW
Ferritin 				HIGH or NORMAL
Transferrin 			normal/low
Transferrin saturation 	normal

Question 16

What are the parameters of thalassemia?

Answer 16

Hb LOW
MCV LOW
Serum iron NORMAL
Ferritin NORMAL

Transferrin NORMAL
Transferrin saturation NORMAL