What is ferroportin?
Ferroportin is the body's most important protein for transporting iron. It functions as the only known iron exporter in humans and is responsible for transporting iron from the body's cells into the bloodstream, where it can be used for, among other things, the formation of red blood cells. Without functioning ferroportin, iron cannot be released from the body's stores, which means that iron metabolism is disrupted even if the body's iron stores are normal or elevated.
The protein is encoded by the SLC40A1 gene and occurs primarily in intestinal cells, macrophages that recycle iron from old red blood cells, liver cells and the placenta. Ferroportin is therefore a central part of the body's regulation of iron uptake, recycling and storage.
In recent years, ferroportin has gained increasing importance in research because ferroportin, together with the hormone hepcidin, is at the core of the body's regulation of iron metabolism. Disturbances in the function of ferroportin can contribute to both iron deficiency, functional iron deficiency and certain forms of iron excess.
The function of ferroportin in the body
Ferroportin functions as a transport channel that carries iron from the cells to the bloodstream. Once the iron has left the cell, it binds to transferrin, which transports it to the bone marrow where it is used to form hemoglobin.
Ferroportin is found primarily in:
- intestinal cells where the absorption of iron from the diet is regulated.
- macrophages that recycle iron from old red blood cells.
- liver cells where iron is stored.
- placenta where iron is transported from the mother to the fetus.
By controlling how much iron leaves these cells, ferroportin determines how much iron becomes biologically available to the body's tissues.
How is ferroportin regulated in the body?
The most important regulator of ferroportin is the hormone hepcidin. When hepcidin levels rise, the hormone binds to ferroportin on the surface of cells. This leads to ferroportin being broken down and disappearing from the cell membrane.
The consequence is that:
- less iron is absorbed from the intestine.
- less iron is released from the body's stores.
- less iron becomes available to the bone marrow.
- red blood cell production may decrease.
If hepcidin levels are instead reduced, more ferroportin molecules become active, which means that the body can increase both iron absorption and the release of stored iron.
Why is ferroportin analyzed in healthcare?
Ferroportin is currently analyzed primarily in research and specialist medicine. The analysis is not routinely used in primary care, but interest is increasing because the marker can provide a deeper understanding of how the body handles iron in complex disease states.
Analysis of ferroportin may be of interest in:
- suspected of unusual disorders in iron metabolism.
- hereditary forms of hemochromatosis.
- difficult-to-interpret iron deficiency.
- functional iron deficiency.
- anemia in chronic inflammation.
- lack of effect of iron therapy.
In clinical practice, Ferritin, iron, Transferrin, transferrin saturation, CRP and blood status are still mainly used to assess your iron status.
Ferroportin and functional iron deficiency
One of the most important clinical roles of ferroportin is its connection to functional iron deficiency. During inflammation, the liver produces more hepcidin, which leads to the breakdown of ferroportin.
The result is that iron is "locked up" in macrophages and liver cells while the amount of circulating iron decreases. The body can therefore have normal or high iron stores while the bone marrow receives too little iron to produce red blood cells.
This can cause symptoms such as:
- fatigue.
- reduced physical performance.
- brain fog.
- shortness of breath.
- anemia.
- less effective iron therapy via tablet.
Ferroportin therefore constitutes an important link between inflammation and the iron deficiency often seen in chronic disease.
Ferroportin and hemochromatosis
Ferroportin also plays a central role in iron overload. In some people, there are mutations in the SLC40A1 gene that affect the function of ferroportin. This can cause the rare disease ferroportin disease, a form of hereditary hemochromatosis.
Depending on which mutation is present, the disease can lead to:
- iron accumulating in macrophages.
- iron is released uncontrollably into the bloodstream.
- ferritin is greatly elevated.
- the liver gradually stores ever-increasing amounts of iron.
The condition is different from the more common HFE-related hemochromatosis and often requires specialist investigation.
Ferroportin and inflammation
In the event of infection or inflammation, the body's immune system is activated. Part of this defense reaction is to increase the production of hepcidin, which reduces the amount of active ferroportin.
The aim is to limit the amount of free iron in the blood because many bacteria need iron to grow. In the short term, this is a protective mechanism, but in the case of long-term inflammation, the same process can contribute to chronic anemia and functional iron deficiency.
This is seen in, among other things:
- chronic kidney disease.
- heart failure.
- rheumatic diseases.
- inflammatory bowel disease.
- cancer.
Ferroportin and anemia
Because ferroportin regulates how much iron reaches the bone marrow, the protein has a direct impact on the production of red blood cells. Reduced ferroportin activity means that less iron is available for hemoglobin synthesis.
This can contribute to:
- anemia in chronic inflammation.
- anemia in chronic kidney disease.
- functional iron deficiency.
- insufficient effect of oral iron therapy.
Ferroportin is therefore considered an important part of the biological mechanism behind several common forms of anemia.
How is ferroportin analyzed?
Unlike ferritin or transferrin, unfortunately there is currently no established routine analysis of ferroportin in Swedish healthcare. Ferroportin is primarily measured in research studies that study the protein's expression in tissue or analyze genetic changes in the SLC40A1 gene.
When diseases linked to ferroportin are suspected, traditional iron tests are usually used together with genetic testing when justified.
Ferroportin in future diagnostics
Knowledge of ferroportin has increased rapidly over the past two decades. Today, the interaction between ferroportin and hepcidin is considered the most important biological mechanism behind the body's regulation of iron metabolism.
Although ferroportin is not yet routinely analyzed in healthcare, the discovery of the protein's function has changed the understanding of several diseases, including functional iron deficiency, inflammation-driven anemia, and certain forms of hemochromatosis.
Future diagnostics and treatment are expected to increasingly focus on the hepcidin–ferroportin axis, which may provide more personalized treatment for patients with complex disorders of iron metabolism.