It's important to consult your doctor to determine what ferritin level is optimal for you. Ferritin is different than iron; it is a protein that controls the capacity of your body to store and release iron as needed. If ferritin levels are low, you won’t be able to store or release adequate iron into your bloodstream. Ferritin is important for many different mechanisms in your body. Iron is required for adequate T3 and T4 production and utilization. If the body senses low iron storage from low ferritin levels, it won’t produce adequate thyroid hormones. Low ferritin levels can also lead to low energy, weakness, lightheadedness, and brittle hair and nails. If you have the above symptoms, or if you have especially heavy periods, it’s wise to get your ferritin levels checked. Learn more about the reasons why you might always be tired.