Ferritin Test

The ferritin blood test is requested to see how much iron your body has stored for future use. It is the most useful indicator of iron deficiency, as the ferritin stores can be significantly low before any decrease in levels of iron in the blood occurs.

If iron excess is suspected, ferritin may be requested in combination with an iron test and either total iron binding capacity (TIBC), unbound iron binding capacity (UIBC), or transferrin saturation (TSAT). An elevated ferritin in combination with a high iron level and either a low TIBC, low UIBC or an elevated TSAT is diagnostic of iron overload.

Ferritin is most often requested when a doctor thinks a patient has too little iron in their system. The body needs iron to produce healthy red blood cells that carry oxygen around the body. Low iron levels can lead to anaemia and the production of red blood cells that are small (microcytic) and pale (hypochromic). If these typical changes are seen on a “full blood count” then ferritin can be measured to confirm a diagnosis of iron deficiency anaemia.

The test may also be requested when the doctor suspects a patient has too much iron stored in their body. Iron overload occurs in hereditary haemochromatosis (a genetic disorder which causes too much iron to be absorbed from the diet) but can also occur as a result of repeat blood transfusions, excess iron supplementation and in alcoholics with liver disease.

Ferritin levels are low in long-term iron deficiency. Ferritin may also be decreased if your body's protein levels are very low, as in some cases of malnutrition.

Ferritin levels are high in states of long-term iron overload, especially in haemochromatosis. However, ferritin levels can be high for a number of other reasons including inflammatory conditions, infection and liver disease. Further investigation is therefore required before a diagnosis of iron overload can be made.

Most ferritin is located within the cells of the body, with only a small amount in the blood. When there is damage to organs that contain ferritin (especially the liver, spleen, and bone marrow), ferritin levels can become raised even though the total amount of iron in the body is normal. Ferritin is therefore a less useful indicator of iron status when measured in people with liver disease, long-term infections, cancer or autoimmune diseases (which are all associated with organ damage).

Iron deficiency refers to a decrease in the amount of iron stored in the body, while anaemia refers to a drop in the number of red blood cells (RBCs) and/or the amount of haemoglobin within the RBCs. Iron deficiency anaemia typically presents with the finding of decreased numbers of red blood cells on a full blood count. These red blood cells are pale (hypochromic) and small (microcytic). It is usually several weeks after iron stores are depleted that the level of haemoglobin and production of RBCs are affected and iron deficiency anaemia develops.

There are usually few symptoms early in iron deficiency. However, as the condition worsens and anaemia develops, ongoing weakness and fatigue can occur. As the iron levels continue to be depleted further, additional symptoms of anaemia may be present such as shortness of breath and dizziness. If the anaemia is severe then chest pain, headaches, and leg pains may also occur.

Other symptoms characteristic of iron deficiency can also occur. These include pica (cravings for specific substances, such as liquorice, chalk, dirt, or clay), a burning sensation in the tongue or a smooth tongue, sores at the corners of the mouth, and spoon-shaped finger- and toe-nails.

Children with iron deficiency can develop learning (cognitive) disabilities.