Iron deficiency can be diagnosed with a simple blood test. Serum ferritin is a marker of the iron stores in the body. When the blood concentration falls below 30ng/mL, the body no longer has enough iron and a patient is probably experiencing many of the symptoms of iron deficiency.
Serum ferritin between 30-100ng/mL indicates low iron stores. Only with serum ferritin levels above 100ng/mL can we be sure that we have enough iron in our body.
Serum iron, which sounds like it would be the best marker for iron levelsc unfortunately only gives an indication of the iron circulating in the blood – this is basically a marker of what we have eaten in last 24h and does not give an accurate reflection of iron stores (and can even be high despite having iron deficiency). Conversely, serum Ferritin (a reflection of the iron stores) is recognised as the most accurate test and best indicator for determining iron deficiency.
In case of an ongoing inflammation or infection, iron saturation (% Fe saturation), is a more reliable indicator as serum ferritin levels might be artificially increased. This is basically the ratio of the iron in the blood (measured by serum iron) and the total iron binding capacity. By looking at the 2 in conjunction we can determine if patients might not be transferring the needed amount to bone marrow and other applicable locations for use.
Our medical experts do not diagnose iron deficiency based on lab results but take history and symptoms into consideration.
Knowing iron levels early may avoid the need for therapeutic interventions (not to mention anaemia).