What Is Ferritin and What Should Your Level Be? What Low Ferritin Means

In brief:

• Ferritin shows your iron stores; if it is low, your stores have fallen (MedlinePlus).
• The WHO threshold in a healthy adult is 15 µg/L. If there is inflammation or infection, the threshold rises to 70 µg/L.
• Many conditions, such as inflammation, liver disease, obesity and alcohol, raise ferritin; high ferritin does not always mean too much iron (MedlinePlus).
• People with heavy periods, pregnant women and people who do not absorb nutrients well may be tested even without symptoms (MedlinePlus).
• Review your result with the range on your report, your other blood tests and your doctor.

What is ferritin?

According to MedlinePlus, ferritin is a protein that binds iron and stores it in the body. The body needs iron to make healthy red blood cells. Iron is also important for muscles, bone marrow and organs.

A ferritin test measures the ferritin level in the blood and shows how much iron is stored in the body. It is usually ordered as part of iron tests (MedlinePlus). We explain iron deficiency in general in Iron Deficiency Symptoms.

Why is a ferritin test done?

According to MedlinePlus, a ferritin test may be ordered:

• If you have symptoms that suggest low iron: shortness of breath, weakness or tiredness, dizziness, an irregular heartbeat, pale skin, restless legs.
• If you have symptoms that suggest too much iron: weakness or tiredness, joint pain, tummy pain, grey, metallic or bronze skin discolouration, low sex drive.
• Without symptoms, in people at risk: those who are underweight, have heavy periods, are pregnant or do not absorb nutrients well (for example people with inflammatory bowel disease or who have had stomach or bowel surgery).
• If other tests are low: if haemoglobin or haematocrit is low.
• To monitor treatment: if iron deficiency or overload is being treated.

Blood is taken from a vein in the arm; it usually takes less than five minutes. Your doctor may ask you to fast for 12 hours; the test is usually done in the morning (MedlinePlus). We explain when ferritin is checked alongside other routine tests in Tests Every Woman Should Have Once a Year.

What should your ferritin level be?

Thresholds from the WHO's 2020 guideline (µg/L; same as ng/mL):

According to the WHO, the 150 µg/L limit for the risk of iron overload is for women who have periods; for men and women without periods the limit is 200 µg/L. In unwell adults, above 500 µg/L may point to iron overload or another illness; further investigation is needed.

What to know when reading these thresholds:

• The WHO rates the certainty of the evidence for these recommendations as "low".
• Laboratories have their own reference ranges; the range on your report may differ from this table.
• Ferritin alone is not used to diagnose iron overload (WHO).
• Your doctor interprets the result together with your age, symptoms and other tests.

What does low ferritin mean?

According to MedlinePlus, lower than normal ferritin may point to iron deficiency anaemia or another condition linked to low iron. Iron deficiency anaemia is when the body cannot make enough red blood cells because of a lack of iron. If untreated, it can lead to heart problems and infections.

According to the NHS, two very common causes of iron deficiency in women are heavy periods and pregnancy. We explain the signs of heavy periods in How Long Does a Period Last?.

Why is ferritin high?

According to MedlinePlus, higher than normal ferritin can show there is too much iron in the body. Other conditions that can raise ferritin:

• Inflammation, such as after an infection or surgery
• Autoimmune diseases
• Liver disease
• Cancer
• Obesity
• Alcohol use disorder
• An overactive thyroid (hyperthyroidism)

According to MedlinePlus, a result outside the normal range does not always mean you have a condition that needs treatment. Some medicines can also lower or raise ferritin.

What can make a ferritin result misleading?

Inflammation and infection: ferritin rises with inflammation. So in someone with an infection or inflammation, the iron stores may be empty even if ferritin looks "normal". In this case the WHO recommends raising the iron deficiency threshold in adults from 15 to 70 µg/L. Two blood tests are used to detect inflammation: CRP and AGP (WHO).

Medicines and supplements: according to MedlinePlus, some medicines can affect ferritin. Tell your doctor about any medicines and supplements you take.

When should you see a doctor?

• Your ferritin result is outside the range on your report: show it to your doctor rather than interpreting it yourself
• You have symptoms of low iron such as tiredness, shortness of breath, dizziness or restless legs (MedlinePlus)
• Your periods are heavy (NHS)
• You are pregnant or planning a pregnancy
• You have symptoms of iron overload such as joint pain or bronze skin discolouration (MedlinePlus)

Do not start iron supplements on your own without checking your ferritin result. Leaving either a deficiency or an overload untreated can cause health problems (MedlinePlus).

Frequently asked

What should ferritin be in women?

According to the WHO, ferritin below 15 µg/L (15 ng/mL) in a healthy adult woman indicates iron deficiency. In a woman who has periods, above 150 µg/L may mean a risk of iron overload. Laboratory ranges differ; check the range on your report.

Is a ferritin of 10 low?

In a healthy adult, 10 µg/L is below the WHO iron deficiency threshold of 15 µg/L. Talk to your doctor about the result; other tests may be needed to find the cause.

What causes high ferritin?

Too much iron in the body, inflammation, infection, liver disease, obesity, alcohol use, autoimmune diseases and hyperthyroidism can raise ferritin (MedlinePlus). A high result does not always mean too much iron.

Do you need to fast for a ferritin test?

According to MedlinePlus, your doctor may ask you to fast for 12 hours and the test is usually done in the morning. Follow your doctor's or the laboratory's instructions.