serum ferritin · iron stores
Ferritin: what your result means
Ferritin is the closest thing to a fuel gauge for the iron your body has in store. It is also an inflammation marker, which is why a high result rarely means what people assume it does.
What it measures
Ferritin is the protein that stores iron inside cells, and the small amount circulating in your blood tracks how much iron your body has put away. It is the best routine test of iron stores — better than serum iron, which swings with what you had for breakfast.
Why it gets tested
Usually to explain tiredness, breathlessness, hair loss or a low haemoglobin, and to tell iron-deficiency anaemia apart from other kinds. It is also checked in heavy menstrual bleeding, in pregnancy, after bariatric surgery, in coeliac disease, in regular blood donors, and where haemochromatosis runs in the family.
Typical ranges
Adult intervals typically run around 30–300 µg/L for men and 15–200 µg/L for women, but laboratories differ substantially. Many clinicians treat ferritin below 30 µg/L as iron deficiency whatever the printed lower limit says, and below 100 µg/L can still be deficient when inflammation is present.
Compare against the range printed on your own report, not this one. Laboratories differ, and yours is the one your doctor is reading.
What a high result can mean
Most high ferritin is not iron overload. Ferritin is an acute-phase protein, so almost anything that inflames raises it — infection, liver disease, heavy alcohol use, obesity, metabolic syndrome, autoimmune conditions. Genuine iron overload, such as hereditary haemochromatosis, is the less common explanation and is usually distinguished by a high transferrin saturation measured alongside it.
What a low result can mean
A low ferritin means depleted iron stores, and it is the earliest sign of iron deficiency — it falls long before haemoglobin does, so you can be iron deficient with a completely normal blood count. Common causes are menstrual blood loss, pregnancy, poor absorption (coeliac disease, gastric surgery, some medicines), a diet low in absorbable iron, and bleeding in the gut, which in an adult man or a postmenopausal woman is the possibility that has to be excluded.
What moves it
Inflammation of any kind pushes it up, which can hide a deficiency underneath an ordinary-looking number. It rises with alcohol and liver injury, and can stay raised for weeks after an infection. Iron tablets and infusions raise it too, so timing matters: a ferritin measured shortly after treatment reflects the treatment, not your stores.
What usually happens next
A low result usually leads to a search for where the iron is going, and to replacement. A high one is normally repeated together with transferrin saturation, CRP, liver enzymes and a look at alcohol and weight — those together separate inflammation from true overload, and only the second leads on to genetic testing for haemochromatosis.
Common questions
Can my ferritin be normal and I still be iron deficient?
Yes. Ferritin rises with inflammation, so an ordinary-looking result can sit on top of empty stores. Where there is inflammation — a raised CRP, a chronic condition, obesity — many clinicians raise the threshold they treat as deficient and look at transferrin saturation as well.
Does a high ferritin mean I have haemochromatosis?
Usually not. Inflammation, fatty liver, alcohol and metabolic syndrome are far more common explanations. Haemochromatosis is generally accompanied by a high transferrin saturation, which is why that test is done alongside before anyone reaches for genetics.