What is the difference between low ferritin and low haemoglobin?

You’ve had bloodwork done and been told your ferritin is low, but your haemoglobin is normal. Does that mean your iron is fine? Or that you’re anaemic?

It can be confusing because these results are related, but they tell your clinician different things. Ferritin helps assess your stored iron. Haemoglobin is the protein in red blood cells that carries oxygen around your body.

What does ferritin tell you?

Think of stored iron as your body’s reserve. Ferritin is one of the tests used to assess that reserve. Iron stores can fall before haemoglobin does, so it is possible to have iron deficiency without anaemia.

Ferritin also needs to be interpreted in context. Inflammation can raise it, which means a result within the laboratory’s reference range does not always settle the question. Your history and other test results help complete the picture.

What does haemoglobin tell you?

Haemoglobin is measured as part of a complete blood count, or CBC. A low result can indicate anaemia, but it does not tell you the cause on its own.

Iron deficiency is one possible cause. Other nutrient deficiencies and chronic illnesses can also contribute. Looking at the pattern is more useful than treating one number as the whole answer.

Why might your iron stores be low?

Blood loss, difficulty absorbing iron and changes in iron requirements are all worth considering. Heavy periods, digestive symptoms and previous iron treatment are useful details to share, rather than reasons to assume a particular cause.

Feeling tired can prompt a conversation, but tiredness alone cannot diagnose iron deficiency or tell you which treatment you need.

What should you bring to your appointment?

Bring recent and earlier bloodwork, a list of medications and supplements, and details of any iron treatment you’ve tried, including difficulties taking it.

A useful question is: ‘Do my results show iron deficiency, anaemia, or both?’ Then ask what might explain the results, which options fit your situation and how progress will be checked.

You can learn about iron assessment and infusion care at EBL. An assessment does not automatically lead to an iron infusion; the recommendation depends on your results, history and treatment needs.

This article is general education. Individual results need individual interpretation.

Sources

Canadian Blood Services. Iron and donor health.

NIH Office of Dietary Supplements. Iron — Health Professional Fact Sheet.

National Heart, Lung, and Blood Institute. Iron-Deficiency Anemia.