Iron studies
Ferritin blood test
A ferritin blood test measures ferritin, the protein your body uses to store iron. It is the earliest and most sensitive marker of iron deficiency, usually falling before the iron in your blood or your haemoglobin does, so a low ferritin can flag depleted iron stores well before anaemia appears.
- What it measures
- Stored iron (the protein ferritin)
- Sample
- Venous blood sample
- Fasting
- Not required
- Also known as
- serum ferritin, iron stores
- Included in 57 Health tests
- 7 panels, from £95
Ferritin reference range
Guide only| Category | Guide range |
|---|---|
| Men (adult) | 30–400 µg/L |
| Women (adult) | 15–200 µg/L |
Iron deficiency is commonly considered likely below about 30 µg/L, and stores are depleted below ~15 µg/L (NICE/WHO). Ferritin can be falsely normal or high when inflammation is present, so it is read alongside CRP and transferrin saturation. µg/L is the same as ng/mL.
These are general UK adult guide ranges from public health sources, shown for orientation only. Reference ranges vary by laboratory, assay, age and sex, so your result is always interpreted against the range quoted by the analysing laboratory on your report.
What does a high ferritin level mean?
A high ferritin most often reflects inflammation or infection rather than iron overload, because ferritin rises as part of the body's “acute-phase” response to illness, injury and even hard exercise.
When it stays high without that explanation, it can point to iron overload (such as haemochromatosis), liver disease, heavy alcohol use or metabolic syndrome. It is interpreted alongside markers like CRP, transferrin saturation and liver function rather than in isolation.
What does a low ferritin level mean?
A low ferritin means your iron stores are low, the earliest stage of iron deficiency. Because stores fall first, you can have a low ferritin while your haemoglobin and full blood count are still normal (iron deficiency without anaemia).
Common causes include heavy periods, low dietary iron, pregnancy, blood loss from the gut, and poor absorption such as in coeliac disease. Endurance athletes are also prone to low ferritin.
When to consider a ferritin test
- Ongoing tiredness or low energy
- Hair thinning or shedding
- Restless legs, or feeling breathless on exertion
- Heavy menstrual periods
- A vegetarian or vegan diet
- Regular endurance training
- Monitoring a course of iron treatment
Frequently asked questions
This page is general information about a blood marker and is not medical advice or a diagnosis. A ferritin test screens and gives context; results are interpreted by a clinician alongside your symptoms, history and other markers. Always follow the guidance on your own report.