Ferritin is an iron-containing protein and is the primary form of iron stored inside of cells. The small quantity of ferritin that is released into the blood is a reflection of the amount of total iron stored in the body. This test measures the amount of ferritin in the blood.
In healthy people, about 70% of the iron absorbed by the body is incorporated into the hemoglobin of red blood cells. Most of the remaining 30% is stored as ferritin or as hemosiderin, a complex of iron, proteins, and other materials. Ferritin and hemosiderin are present primarily in the liver but also in the bone marrow, spleen, and skeletal muscles.
When available iron is insufficient to meet the body's needs, iron stores are depleted and ferritin levels decrease. This may occur because of insufficient iron intake, inadequate absorption, or increased need for iron such as during pregnancy or due to a condition that causes chronic blood loss. Significant depletion of iron stores may occur before any signs of iron deficiency develop.
Iron storage and ferritin levels increase when more iron is absorbed than the body needs. Chronic absorption of excess iron will lead to the progressive buildup of iron compounds in organs and may eventually cause their dysfunction and failure. This happens in hemochromatosis, a genetic disease in which the body absorbs too much iron, even on a normal diet.
Serum Ferritin; Ferritin serum
To determine your body's total iron storage capacity. When your doctor suspects that you may have too little or too much iron in your system.
The ferritin test may be ordered, along with other iron tests, when a routine CBC shows that a person's hemoglobin and hematocrit are low and their red blood cells are smaller and paler than normal (microcytic and hypochromic), suggesting iron deficiency anemia even though other clinical symptoms may not have developed yet.
In the early stage of iron deficiency, no physical effects are usually seen. If a person is otherwise healthy, symptoms seldom appear before the hemoglobin in the blood drops below a certain level (10 g per deciliter). However, as the iron-deficiency progresses, symptoms eventually begin to develop and a doctor may order ferritin as well as other iron-related tests. The most common symptoms of iron deficiency anemia include:
Pale skin (pallor)
As iron stores continue to be depleted, there may be shortness of breath, ringing in the ears (tinnitus), drowsiness, and irritability. If the anemia progresses in severity, chest pain, headaches, leg pains, shock, and even heart failure may occur. Children may develop learning (cognitive) disabilities. Besides the general symptoms of anemia, there are certain symptoms that are characteristic of iron deficiency. These include pica (cravings for specific substances, such as licorice, 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.
A ferritin level may also be ordered when iron overload is suspected. Symptoms of iron overload will vary from person to person and tend to worsen over time. They are due to iron accumulation in the blood and tissues. Symptoms may include:
Lack of energy
Loss of sex drive
Loss of body hair
Heart problems such as congestive heart failure (CHF)
To confirm the presence of iron overload, other iron tests (iron, TIBC) and a genetic test for hereditary hemochromatosis may be ordered as well.