A Ferritin blood test measures the levels of ferritin in your blood. The test can also indirectly measure the levels of iron found in your blood by calculating the amount of ferritin. Ferritin is a protein found within cells and can be directly related to volume of iron stored in your body.
If a ferritin test highlights that your blood ferritin levels are lower than normal it could show that you have and iron deficiency as a result you may be suffering with anemia.
When a ferritin test shows that the blood ferritin levels are higher than usual it could indicate that your body stores too much iron.