Appropriate Starting Dose for Supplemental Iron in Adults with Iron Deficiency Anemia

First-Line Oral Iron Therapy

The American Gastroenterological Association recommends starting with 50-100 mg of elemental iron once daily, taken in the morning on an empty stomach, using ferrous sulfate 200 mg tablets (which provide 65 mg elemental iron) as the first-line agent, with a cost of approximately $1.00 for a 28-day supply 1, 2
A single daily dose of 50-100 mg elemental iron is optimal, as doses ≥60 mg stimulate hepcidin elevation that persists for 24 hours and blocks subsequent iron absorption, with a strength of evidence level of high 1, 2

Hemoglobin should rise by at least 10 g/L within 2 weeks of starting daily oral iron therapy, with a sensitivity of 90.1% and specificity of 79.3%, according to the American Society of Hematology 1, 2
The European Hematology Association recommends monitoring hemoglobin within the first 4 weeks to confirm adequate response and detect non-responders early 1, 2
Treatment should be continued for approximately 3 months after hemoglobin normalizes to ensure adequate repletion of iron stores, as suggested by the National Institute for Health and Care Excellence 1, 2

The American College of Physicians recommends considering intravenous iron replacement for patients in whom oral iron is not effective, not absorbed, or not tolerated, or presenting with severe anemia, with a strength of evidence level of moderate 3
Intravenous iron should be first-line in patients with chronic disease, continuing blood loss, impaired absorption, or gastrointestinal inflammatory pathology, according to the European Society for Medical Oncology 1, 2
Parenteral iron produces a clinically meaningful hemoglobin response within one week and should be considered as an alternative to blood transfusion in most cases, as recommended by the American Society of Clinical Oncology 1

The National Institutes of Health recommends considering taking iron with vitamin C (250-500 mg), which enhances absorption by forming a chelate with iron, with a strength of evidence level of high 2
The American Gastroenterological Association suggests avoiding concurrent use of H2-blockers or proton pump inhibitors, which impair iron absorption, with a strength of evidence level of moderate 4, 5