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What is ferritin?

Iron is an essential bioelement for life; however, free ionic iron is toxic and must be correctly stored inside the cell. Ferritin is the main protein that stores safely the iron inside the cell. This protein is expressed in all the organism cells.

Tissue ferritin (ferritin that is inside the tissues) is composed by 24 subunits of two types of ferritins named: L chain (light, 19 kDa, chromosome 19) and H chains (heavy, 21 kDa, chromosome 11). The proportion of each subunit varies according to the need for storage and homeostasis of the cell. These subunits form a spherical cavity which stores the free iron (Fe2+) and saves it therein in the form of Fe3+, through the action of the H-ferritin ferroxidase activity. Thus, ferritin consists of a soluble protein (apoferritin) and an inner layer composed of ferric hydrophosphate.

Plasma or serum ferritin, is secreted by all ferritin-producer cells and unlike tissue ferritin it is partially glycosylated and nearly completely iron-free. Serum ferritin is currently regarded as the main test for deficiency states or body iron overload, since its value is proportional to iron stores, indicating the amount of iron available in the body. Each microgram of plasma ferritin per litre (µg;/L) is equivalent to between 8-10 milligrams of iron deposit. Normally, a low level of ferritin indicates a low level of iron (Iron Deficiency Anaemia). However, a high level of ferritin may indicate various pathologies, including inflammation or infection, since this protein is an acute phase reactant that increases its concentration in that context.


What means high levels of serum ferritin?

High values ​​of ferritin usually indicate high levels of iron, but this is not always the case. High levels of ferritin or hyperferritinemia is associated with diseases or conditions such as:


What means VERY high levels of serum ferritin (>1000 µg/L)?

There are several evidences that indicate that a serum ferritin level greater than 1000 µg/L is highly associated with a severe impairment of the parenchyma, especially the liver parenchyma. These patients should be tested for liver iron concentration using a direct method. Types of medical tests that can be done are:

In those patients with significant iron overload demonstrated by biopsy or MRI further studies in specialized laboratories are required.

If the rate of transferrin saturation (TS) is greater than 45% the following genetic studies are recommended:

If the rate of transferrin saturation (ST) is less than 45% following genetic studies are recommended:

Genetic studies in specialized laboratories can confirm the disease diagnostic in iron loading anaemias and hereditary hemolitic anaemias. Genetic studies:


What kinds of tests are needed to do with people with high serum ferritin levels?

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