Chronic heavy periods can result in iron deficiency, which can lead to anemia. Anemia is a low hemoglobin when measured by a blood test (CBC or complete blood count). The best measure of iron stores is a ferritin, which can also be measured by a blood test. Symptoms of iron deficiency anemia include fatigue, weakness and lack of energy. In severe cases, shortness of breath and chest pain (particularly with activity) can occur. Brittle nails and hair loss are also associated. It is important to take iron replacement if you are iron deficient in order to replace iron stores as it is difficult to correct the problem by increasing dietary iron intake alone.