The ferritin test measures the amount of ferritin in the blood. Ferritin is a protein found principally in the liver, spleen, skeletal muscles, and bones that stores iron so your body can use it later. As free iron in the blood is toxic to your cells, the majority of iron stored in your body is found in ferritin. Because of this, the ferritin test is the best test to measure the amount of iron in your body.
Low ferritin levels may indicate a lack of iron which can lead to anemia. Low ferritin levels have also been associated with restless leg syndrome, ADHD in children, and hypothyroidism. Elevated Ferritin levels are typically associated with iron overload disorders and periods of disease or acute malnourishment.