Iron deficiency explained

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You have 3000-4000mg in the body and only need to absorb 4-10mg a day. It can take 3-7 years to develop #irondeficiency. Iron deficiency is indicated by #Ferritin < 16 and transferrin saturations < 18% – when this low you can become #anaemic Hb<13 with small red cells MCV<80. At this point the body is #empty of iron and you need at least 1000mg to catch up.

Do the math if you are iron deficient you need at least 100-200 days of good iron absorption (4-10mg per day) to restore your #irondeficiency.

Intravenous iron is used when there is failure of oral iron – so no improvement after 6-12 weeks. The treatment is an iron infusion. This is good news as an #ironinfusion will restore 1000-1600mg in one go and therefore restock your iron stores.

What is iron deficiency?

Test Result Medical Term Meaning
Ferritin < 15 Absolute Iron Deficiency EMPTY there is no petrol in the tank
Ferritin < 30 Iron Depleted On the reserve tank



Good well balanced diet rich in Iron (meat), no alcohol or tea/coffee. Iron tablets (65mg elemental iron a day – if intolerant, try alternate days)

What is failure of treatment

If anaemic – Hb does not increase by 1g/dl or 10g/L over 1 month
If iron deficient – Ferritin does not increase over 30 in 3 months

Iron Infusion

Failure of oral iron or intolerant then get an iron infusion. You need 20mg of iron per KG body weight so if 75kg then 1500mg.

I am ill is it the same?

In a hospitalised patient such as after surgery or a patient where there is active disease-causing inflammation (kidney disease or inflammatory bowel disease) then Ferritin is not accurate so:

Ferritin & tsats < 100
< 20
functional Iron Deficiency Normal service is ‘On Strike’
If you want iron – get an infusion

Author: Professor Toby Richards

Mr Toby Richards is a Professor of Surgery at University College London. He has pioneered anaemia management and intravenous iron therapy in the UK. His underlying belief is that optimising patient’s health and fitness before surgery will improve their recovery and benefit their outcomes. He has embedded clinical research and development into all areas of practice.

Book an appointment..

You can download our patient information sheet: Patient Information Sheet

To book an appointment please email us a short history and copy of your blood results, we will respond with options about online or in person consultations and availability for an infusion (normally most Monday and Friday afternoons):

Our staff are available and happy to answer your every question

020 3875 8171