Your result falls within the reference range, so "everything is fine," they say. But your ferritin reads 18 and you drag yourself through the day. Something does not add up here, and it is one of the most common misunderstandings around iron: being within the reference range is not the same as being optimal.
My view: a ferritin just inside the lower limit with ongoing complaints deserves a conversation, not a shrug. The lab's lower limit is not a threshold for feeling good, it is a statistical boundary.
What is ferritin?
Ferritin is a protein that stores iron, mainly in your liver, spleen and bone marrow. A small amount circulates in your blood, and that value reflects your total iron store. Unlike serum iron, which fluctuates by the day, ferritin gives a more stable picture of your iron status.
Normal ferritin ranges
| Group | Reference range (ug/L) | Note |
|---|---|---|
| Men | 30 to 300 | High may point to iron overload or inflammation |
| Women (premenopausal) | 15 to 150 | Below 30 sometimes already causes symptoms |
| Women (postmenopausal) | 30 to 300 | Comparable to men |
Note: some doctors use a lower limit of 30 ug/L for optimal functioning in women, even though 15 ug/L is formally within range. Below 30 ug/L, complaints such as fatigue and hair loss can already appear.
Ferritin too low: what does it mean?
A low ferritin points to depleted iron stores. Possible causes:
- Insufficient intake: vegetarian or vegan eating, a one-sided diet
- Increased loss: heavy menstruation (the most common cause in women), chronic gastrointestinal blood loss
- Increased need: pregnancy, intensive sport, growth in children
- Reduced absorption: coeliac disease, acid blockers, inflammatory bowel disease
Symptoms of low ferritin: fatigue, concentration problems, paleness, hair loss, cold hands and feet, and restless legs.
Ferritin too high: what does it mean?
A high ferritin does not automatically mean too much iron. Ferritin also rises with inflammation.
- Inflammation or infection: ferritin is an acute-phase protein and rises independently of your store. This is the most common cause of a raised value.
- Liver disease: damaged liver cells leak ferritin
- Haemochromatosis: a hereditary condition where the body absorbs too much iron
- Excessive supplementation: unnecessarily high doses of iron tablets
- Heavy alcohol use: chronic excess can raise ferritin
Because inflammation distorts the value, your doctor can add CRP to rule it out.
What to do at which level?
The guide below is a tool to put your result in perspective, not a replacement for your doctor's advice. The exact thresholds differ per laboratory and per person.
| Ferritin (ug/L) | What it usually means | Sensible next step |
|---|---|---|
| Below 15 | Very likely depleted | Discuss the cause and approach with your GP |
| 15 to 30 | Low, symptoms possible | Discuss with complaints such as fatigue or hair loss |
| 30 to 150 | Generally sufficient | No action needed without symptoms |
| Above the reference range | Iron overload or inflammation | Have CRP added and consult your doctor |
Important: a single value is a snapshot. If you have complaints while your ferritin sits just inside the range, a conversation with your GP is more useful than supplementing on your own. And a high value is not automatically a cause for concern, because inflammation is the most common explanation.
Testing ferritin
Ferritin is measured with a standard blood draw. Fasting is not strictly required, though some doctors advise it for the most reliable value. Pause iron supplements ideally 24 hours before the test. For a complete picture, ferritin is often combined with haemoglobin, MCV and transferrin.
Frequently asked questions
Can ferritin be normal while I still have iron deficiency?
Yes, if there is inflammation at the same time. It raises ferritin artificially. Your doctor can then use transferrin saturation or CRP to uncover the real iron level.
How quickly does ferritin rise after supplementation?
Ferritin rises more slowly than haemoglobin. It can take 3 to 6 months for your store to fully replenish, even if your haemoglobin normalises earlier.
Is a ferritin of 20 ug/L too low?
Formally it is within the reference range for women (15 to 150). In practice, complaints can appear below 30, especially fatigue. Discuss a ferritin below 30 with your doctor if you have symptoms.
Do I need to fast for a ferritin test?
It is not strictly required, as ferritin is fairly stable. Some doctors advise it anyway, especially if serum iron is drawn at the same time, since that value can fluctuate after eating. Pause iron supplements ideally 24 hours before the draw, otherwise you can get a distorted picture.
Can exercise lower my ferritin?
Intensive endurance sport can increase iron use and contribute to a lower ferritin, especially in women. That is no reason to stop exercising, but it is a reason to check your iron status now and then if you train a lot and have complaints.
Want to view your ferritin in context? An iron studies panel measures the relevant values together, or build a custom blood test. Read also how to detect iron deficiency and what iron storage involves. Every result at Vitalcheck is reviewed by a registered doctor. A blood value is not a diagnosis: discuss symptoms and treatment with your GP.
Sources
- NHG guideline Anaemia. Dutch College of General Practitioners. Accessed 2026.
- Gezondheidsraad (Health Council of the Netherlands). Dietary reference values for vitamins and minerals. 2018.
- Thuisarts.nl / NHG. Anaemia due to iron deficiency. Accessed 2026.
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