Ferritin test: the earliest sign of low iron stores

Your ferritin level says something about the amount of iron your body holds in reserve. A low ferritin level is often one of the earliest signs of a deficiency. It can show up before other blood values change.

Iron is needed to make red blood cells. When stores run low, that production suffers over time. A ferritin test shows whether your reserve is still adequate. It is not a diagnosis, but a starting point for a conversation with your doctor.

This test may be of interest to women who:

• often feel tired or low on energy
• notice more hair fall than usual
• have heavy or long periods
• eat a vegetarian or vegan diet
• want to conceive or have recently given birth

Menstruating women lose blood every month. That makes them more prone to a deficiency. For them this test is suitable as a periodic check.

This test measures a single blood value:

• Ferritin: the protein that stores iron and reflects your reserve. Read our explanation of ferritin for the full reference ranges.

The ferritin measurement is carried out in a certified laboratory. A serum iron reading alone does not show your reserve. This value does.

A low value can point to an iron deficiency. That happens when your body takes in too little iron. It also occurs through blood loss, for example during a heavy period.

A high value sometimes fits with inflammation. Less often it points to too much iron. The best-known form of that is iron overload (haemochromatosis), an inherited condition.

What your value means depends on your symptoms and your situation. The doctor assesses that for you.

Dutch laboratories report the value in micrograms per litre. That unit is written as µg/l. In women the expected range usually falls between 15 and 150 µg/l.

In men the range runs from 30 to 400 µg/l. Labs abroad often use ng/ml. The two units are equal to each other. One ng/ml is therefore one µg/l.

The range differs by laboratory and by age. Your result therefore always carries the reference range of the lab that analysed your blood.

Blood is drawn at a certified sample point. There are 700+ locations across the Netherlands. You can usually pick one close to home.

After ordering you choose a sample point and a time that suits you. Trained staff draw the blood. The sample then goes to the laboratory.

You might consider this test when:

• you feel persistently tired without a clear reason
• you notice more hair fall or find it harder to concentrate
• you have heavy periods and want to track your iron stores
• you eat a plant-based diet and want to know where you stand

Ferritin is not linked to your cycle. You can have blood drawn on any day of the month. That makes planning a good deal easier.

Your result is available online within a few working days. You see your value, the reference range and a clear explanation.

If a result falls outside the range, the doctor explains what may be going on. Is a low ferritin level behind your symptoms? Discuss that with your GP. Always take treatment decisions together with a doctor.