Ferritin level: what does your result mean?

What exactly is ferritin? It is a protein that holds and stores iron, mainly in your liver, spleen and bone marrow. A small part of it leaks into your blood, and that is the part we measure. So how much iron you have in store is what your ferritin tells you.

A comparison helps most. Serum iron is what is circulating right now, and it changes throughout the day, including after eating. Ferritin is your store cupboard and moves much more slowly. If you are wondering whether you have enough iron, ferritin is the value you want, not serum iron.

A normal ferritin level looks like this at the lab that performs our tests:

In women the lower limit sits lower because the group those figures come from includes menstruating women, who lose iron every month. So it describes what is usual, not a statement that women need less iron.

Important: these figures genuinely differ between laboratories. Another lab uses 15 to 200 for men, for instance. Two national bodies therefore say you should go by the values on your own report. If your result shows a different band from the one above, yours is the right one. Beyond that, always look at it together with your haemoglobin and your CRP.

If you remember one thing about your ferritin level, make it this: ferritin rises with inflammation. If you have an infection, an injury, an autoimmune condition, a liver problem, or you drink a lot of alcohol, your ferritin goes up while your iron store stays the same. A normal figure is then not reassuring, because it can hide a deficiency. That is why a CRP always belongs beside it. It tells you whether inflammation is involved and therefore which threshold applies.

Then the numbers your doctor uses. Without inflammation: below 15 µg/l means iron deficiency. With inflammation, that threshold rises to around 70 µg/l, precisely because the inflammation lifts the figure artificially. And for iron-deficiency anaemia the GP standard works with three zones: below 15 confirms it, above 100 excludes it, and in between you do not yet know.

That middle zone between 15 and 100 is where most confusion arises. Your result falls inside the reference values, so formally nothing is wrong, yet your complaints are real. That is not a contradiction. Your iron store empties before your haemoglobin falls, so you can be tired, lose hair or have restless legs with an entirely normal blood count. The literature often uses around 30 µg/l for a genuinely empty store, well above the 15 at which anaemia is established.

In short: one ferritin figure without context says little. Together with your CRP, your haemoglobin and your transferrin saturation it says almost everything. So request them together and you avoid a second blood draw.

You usually have ferritin measured because you are tired and want to know why. That is a perfectly good reason. Other good prompts are hair loss, restless legs, breathlessness on stairs, frequent dizziness, or an earlier result where your doctor noticed something in your blood count, such as a low haemoglobin or small red cells.

You do not need to fast and no fixed time of day is required. There is one timing rule that genuinely matters though: do not test during or shortly after an infection. If you have just been ill, had surgery or trained hard for a week, wait a few weeks. Ferritin runs higher in that period and that can hide a deficiency.

Always request a CRP alongside. Without it you cannot interpret a normal or high result and you will probably need another draw anyway. If you are having the full iron panel, test in the morning: serum iron fluctuates across the day and the set then compares better internally.

If you want to know whether iron really is the issue, also look at your haemoglobin and your MCV. The latter says how large your red cells are, and with a longer-standing iron deficiency they get smaller. Together with your ferritin that gives a far more complete picture than one value alone.