between appointments · 7 min
Ferritin is low but haemoglobin is normal. Does that happen?
In short: yes, and often. Ferritin shows your iron stores, while haemoglobin drops only once the stores are nearly used up. This is called iron deficiency without anaemia. The cause and the treatment are for a doctor to decide.
What ferritin shows
Ferritin is the protein your body stores iron in, so its level reflects your iron stores. Haemoglobin carries oxygen in red blood cells, and iron is needed to make it.
When iron runs short, the body uses up its stores first, so ferritin falls. Haemoglobin stays normal for a long time and drops only when the stores are almost gone. That is why low ferritin with normal haemoglobin is common.
Why it happens
Common causes: heavy periods, pregnancy, a diet low in iron, frequent blood donation. Sometimes iron is poorly absorbed or lost unnoticed, for example with stomach or bowel conditions.
It can also go the other way: inflammation raises ferritin, so it may look normal even when iron is short. That is why it is read together with other values, and that is a doctor's job.
What to do
Don't start taking iron on your own. The doctor chooses the medicine, dose and duration, and it matters to find the cause, or the stores will run out again.
Show your GP your results from recent months and describe how you feel: tiredness, hair loss, breathlessness on exertion. If you have severe weakness, dizziness or fainting, see a doctor sooner.