?A ferritin blood test is one of the most useful ways to assess iron stores in the body. Not just the iron moving around in your blood at that moment, but the iron your body has saved for later.
That distinction matters.
You can have symptoms of low iron stores before a standard full blood count clearly shows anaemia. You can also have a ferritin result that looks high for reasons that have very little to do with having “too much iron”. Inflammation, liver health, infection, alcohol intake, metabolic health and certain medical conditions can all affect ferritin.
At London Blood Tests, we offer private ferritin and iron profile testing in London, with clinic and home visit appointments available. If you are feeling persistently tired, noticing hair shedding, struggling with dizziness, heavy periods, poor exercise tolerance or unexplained weakness, checking ferritin may be a helpful place to start.
What is a ferritin blood test?
A ferritin blood test measures the level of ferritin in your blood. Ferritin is a protein that stores iron inside the body and releases it when needed.
Iron is essential for making healthy red blood cells. Red blood cells carry oxygen around the body, which is why low iron or low iron stores can make a person feel tired, breathless, weak or light-headed. Ferritin gives an indirect picture of how much iron is stored, especially in tissues such as the liver, spleen and bone marrow.
In simple terms: serum iron tells you more about circulating iron. Ferritin tells you more about stored iron.
This is why ferritin is often checked alongside a full blood count and other iron markers, rather than being interpreted completely on its own.
Ferritin on blood test results: what does it mean?
When you see ferritin on blood test results, it usually appears as a number with a laboratory reference range beside it. The result may be reported in micrograms per litre or nanograms per millilitre, depending on the laboratory.
A low ferritin result often suggests reduced iron stores. A high ferritin result can sometimes suggest iron overload, but it may also rise because ferritin behaves as an inflammatory marker. That means your ferritin may increase during inflammation, infection, liver problems, alcohol-related liver stress, obesity, autoimmune conditions or other health issues.
So, the meaning of ferritin depends on context.
A ferritin result should be interpreted with your symptoms, full blood count, serum iron, transferrin saturation, TIBC, CRP, liver function markers and medical history where relevant. Looking at ferritin alone can be misleading.
Ferritin blood test meaning: low ferritin
The ferritin blood test meaning is usually clearest when ferritin is low. Low ferritin commonly suggests that your stored iron is depleted or running low.
This may happen because of:
· heavy periods
· pregnancy or recent childbirth
· low iron intake
· vegetarian or vegan diets without enough iron planning
· poor iron absorption
· coeliac disease or inflammatory bowel disease
· gastrointestinal blood loss
· frequent blood donation
· intense endurance training
· recent surgery or blood loss
Low ferritin can occur before anaemia is obvious. This is why some people may feel tired, weak or unusually flat even when their haemoglobin is still within range.
Common symptoms linked with low iron stores can include tiredness, lack of energy, dizziness, shortness of breath, palpitations, headaches, pale skin, restless legs, brittle nails and hair shedding. These symptoms are not specific to low ferritin, but they are common reasons people choose to check iron status.
Can ferritin be low even if haemoglobin is normal?
Yes. This is one of the most important points.
A full blood count may show whether you are anaemic, but ferritin can show whether your iron stores are low before anaemia fully develops. This means someone can have normal haemoglobin but still have low ferritin.
This does not mean ferritin explains everything. Fatigue, hair shedding and dizziness can also be linked to thyroid function, B12, folate, vitamin D, hormones, inflammation, infection, sleep, stress or other medical causes.
That is why ferritin is often best checked as part of a broader panel.
For example, someone with tiredness may benefit from checking ferritin together with full blood count, iron studies, B12, folate, vitamin D, thyroid function, liver function, kidney function and inflammation markers. The pattern is often more useful than one result.
Blood test ferritin: high ferritin
A blood test ferritin result can also come back high. This does not automatically mean iron overload.
High ferritin may be seen with:
· inflammation or infection
· liver disease
· alcohol-related liver stress
· obesity or metabolic syndrome
· autoimmune conditions
· kidney disease
· hyperthyroidism
· some cancers
· iron overload conditions such as haemochromatosis
· repeated blood transfusions
· excessive iron supplementation
This is why a high ferritin result should not be treated casually with iron supplements. If ferritin is high, it may be important to check transferrin saturation, liver function, CRP, full blood count and other relevant markers.
A high ferritin result needs proper interpretation, especially if it is significantly raised or persistent.
Serum ferritin blood test vs iron blood test
A serum ferritin blood test is not exactly the same as a serum iron test.
Serum iron measures the amount of iron circulating in the blood at the time of testing. This can vary during the day and may be affected by recent diet, supplements and other factors.
Ferritin gives a better indication of stored iron. However, ferritin can rise with inflammation, which means it is not always a pure reflection of iron storage.
An iron profile may include:
· ferritin
· serum iron
· transferrin
· total iron-binding capacity
· transferrin saturation
· full blood count
· sometimes CRP or other inflammation markers
This gives a more complete picture. For example, low ferritin with low transferrin saturation may support iron deficiency. High ferritin with raised CRP may suggest inflammation. High ferritin with high transferrin saturation may raise the question of iron overload.
Ferritin blood test high: should you worry?
A ferritin blood test high result should be reviewed, but it should not cause panic by itself.
Ferritin can rise temporarily after infection, inflammation, recent illness, surgery or liver stress. It can also be chronically raised in metabolic syndrome, fatty liver, alcohol use, inflammatory conditions or iron overload.
The next step depends on how high the ferritin is, whether it has been raised before, and what the rest of your blood results show.
If your ferritin is high, it may be sensible to check:
· full blood count
· liver function test
· CRP or ESR
· transferrin saturation
· fasting glucose and HbA1c
· cholesterol profile
· kidney function
· alcohol intake and medication history
· family history of haemochromatosis
You should not start or continue iron supplementation if your ferritin is high unless a clinician has specifically advised it.
What is the blood test for ferritin used for?
People searching what is the blood test for ferritin are usually trying to understand whether ferritin can explain symptoms.
Ferritin testing may be useful if you have:
· ongoing fatigue
· low energy
· dizziness
· shortness of breath on exertion
· heavy periods
· hair shedding
· restless legs
· weakness
· headaches
· palpitations
· poor recovery from exercise
· a history of iron deficiency
· pregnancy or postpartum concerns
· vegetarian or vegan diet
· gut symptoms affecting absorption
It can also be useful for monitoring treatment if you have already been advised to take iron.
However, ferritin testing should be part of a sensible plan. If the cause of low ferritin is heavy periods, gut blood loss, poor absorption or diet, that cause needs to be understood. Replacing iron without understanding why it became low can miss the bigger issue.
Do you need to fast before a ferritin blood test?
For many ferritin tests, fasting may not be essential, but preparation can vary depending on the full panel being checked.
If ferritin is being tested as part of a wider iron profile, metabolic panel, cholesterol test or fasting glucose/insulin panel, you may be asked to fast. Some clinicians also prefer morning testing for consistency.
If you are taking iron supplements, it is worth asking whether you should pause them before testing, because recent supplementation can affect some iron markers. Do not stop prescribed treatment without medical advice.
At London Blood Tests, preparation instructions are provided according to the specific test or panel booked.
Ferritin blood test UK: private testing options
A private ferritin blood test uk appointment can be useful if you want faster access, a broader iron profile, or the convenience of choosing clinic or home blood collection.
At London Blood Tests, ferritin can be checked as an individual marker or as part of a wider panel. Depending on your symptoms, you may want to combine ferritin with:
· full blood count
· iron profile
· B12 and folate
· vitamin D
· thyroid function