The ferritin blood test is done to measure the amount of ferritin protein (the major iron storage protein) present in the blood. This test helps to diagnose the presence of any iron-related medical condition and overall health scenario of an individual. The healthcare professional may ask you to do a ferritin test if you have symptoms of too low or too high iron levels. Symptoms of low iron levels may include pale skin, fatigue, weakness, dizziness, shortness of breath, rapid heartbeats, pain in the legs, etc. Symptoms of high iron levels may include joint pain, chest pain, abdominal pain, lack of energy, weight loss, etc. These symptoms may vary and tend to get worse over time.