- Severe iron-deficiency anemia (Hb <9 g/dL) especially if there is ongoing bleeding
- Rate of bleeding too brisk for oral iron
- Time-sensitive pressures (eg, an urgent surgical procedure; observational studies of the use of IV iron preoperatively for patients with anemia have shown a reduced rate of red cell transfusion being required)
- Severe anemia of chronic disease and evidence of iron deficiency (eg, ferritin <30 ug/L)
- Oral iron being poorly tolerated or the failure of an oral trial
- Poor oral absorption (due to conditions including gastric bypass, celiac disease, and gastritis)
IV iron is given as iron sucrose (brand name Venofer) in an infusion of 300 mg in 250 mL of normal saline over two hours. After IV iron, and with ongoing oral supplementation, a patient’s hemoglobin will start to rise in three to seven days. You can expect a 0.1- to 0.2-point rise in the hemoglobin per day; after two to four weeks, the hemoglobin will have risen 2 to 3 g/dL. Ferrous sulfate (300 mg) contains 60 mg of elemental iron, and one tablet can be taken each night on an empty stomach at least two hours after meals with 500 mg of vitamin C to improve absorption. Patients should be counseled to avoid taking iron with calcium or magnesium supplements as they decrease iron absorption.