What is haemochromatosis?

About Iron in the body

Iron is a chemical element that is found in many foods. It’s a very important part of haemoglobin – a protein found in red blood cells.

Haemoglobin in red blood cells attaches to oxygen as blood flows through your lungs. The red blood cells carry the oxygen round your body, releasing it to the body tissues that need it. As well as the iron in haemoglobin, your body stores a little extra iron in the liver, for when it’s needed.

Iron is absorbed in the gut from the food you eat and passes into the bloodstream.  A protein called transferrin picks up the iron in the blood and carries it to the liver for storage or to your bone marrow, where new red blood cells are made.

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How haemochromatosis affects iron in the body

If you have haemochromatosis, your body doesn’t produce enough of a protein called hepcidin. This is a hormone that stops your body absorbing iron from your gut when you don’t need it.

Without hepcidin, your body absorbs too much iron. It has no way of getting rid of the excess iron. So, over time, it builds up. This is mostly in the liver, where it’s been transported by the transferrin protein. If your haemochromatosis isn’t diagnosed and managed, eventually the iron build up can cause damage to your liver and other body organs.

The amount of hepcidin people with haemochromatosis make varies. It depends which genes are affected. People with juvenile haemochromatosis make little or no hepcidin. So iron builds up more quickly, meaning symptoms start at a younger age and are often worse. Adults with the main type of haemochromatosis can usually make some hepcidin. This means any iron build-up is usually slower and symptoms are milder.

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Next: How is haemochromatosis passed on in families?

Published: September 2025

Review date: September 2028

Clinical reviewers: Jeremy Shearman, Consultant Hepatologist and Gastroenterologist, South Warwickshire University Foundation Trust.  Sister Kim Hicks, Medical Day Unit Haemochromatosis Nurse, Royal Cornwall Hospital, Treliske. Dr Indra van Mourik, Consultant Paediatric Hepatologist (retired).

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