Oral and Intravenous Iron Therapy

Pre-anemic iron deficiency and iron deficiency anemia are the most common health conditions. They are mostly caused by blood loss and/or inadequate dietary iron absorption and are managed with iron replacement therapy. The goal of iron replacement therapy is to correct anemia and replenish iron stores. In most patients, oral iron is typically the first choice for treatment due to its ease of use, over-the-counter availability, and low cost of most common formulations. Ferrous sulfate remains the gold standard for oral iron therapy, but alternative formulations have also been developed. Effective iron repletion requires the daily intake of up to 200 mg elemental iron for 3-12 weeks. However, only a small fraction of it gets absorbed. Thus, accumulation of unabsorbed iron in the intestinal lumen may cause constipation and other gastrointestinal side effects. Intravenous iron is the preferred treatment for patients who are intolerant or refractory to oral iron or require rapid correction of anemia and repletion of iron stores, for example prior to surgery. The newest formulations such as ferric carboxymaltose and ferric derisomaltose have excellent safety profiles and can be provided at high doses of 500-1000 mg in a single infusion. Intravenous iron should always be administered in medical facilities by healthcare providers trained to manage potential but rare hypersensitivity reactions. Moreover, phosphate levels should be monitored in patients because intravenous iron formulations, especially ferric carboxymaltose, have been associated with increased risk for hypophosphatemia.