Natural iron stores, or ferritin, in the body are a special type of protein that the body makes to store iron, release it, and benefit from it when needed. The majority of ferritin is usually found inside the various cells of the body, especially in the liver and immune system cells. Ferritin is rarely present in the bloodstream, when needed. By making new red blood cells, the body releases ferritin and transports it to the places where these blood cells are made for use.
It does not require preparations for this test, but may require fasting for several hours if it coincides with other additional blood tests.