According to the Mayo Clinic, lower than normal ferritin levels are indicative that someone has an iron deficiency. Ferritin is a blood cell protein that contains iron.
According to the Mayo Clinic, a ferritin test showing higher-than-normal ferritin levels may indicate that someone has a condition that causes the body to store too much iron. High ferritin levels may also mean that someone has liver disease, rheumatoid arthritis, hypothyroidism or another inflammatory condition. Some kinds of cancer can make blood ferritin levels too high. A blood ferritin test may be performed to diagnose a medical condition or to monitor an existing medical condition.