What is the recommended treatment plan for a patient with iron deficiency anemia?

Treatment Plan for Iron Deficiency Anemia

First-Line Oral Iron Therapy

Start ferrous sulfate 200 mg (65 mg elemental iron) once daily immediately—this is the preferred first-line treatment due to superior cost-effectiveness and equivalent efficacy to all other oral formulations. 1, 2

Dosing Strategy

• Prescribe once-daily dosing only—never multiple times per day. 1 Once-daily or alternate-day dosing improves tolerability while maintaining equal or better iron absorption because hepcidin levels remain elevated for 48 hours after iron intake, blocking further absorption. 1, 3
• Take on an empty stomach for optimal absorption, though taking with food is acceptable if gastrointestinal side effects occur. 1
• Add vitamin C (ascorbic acid) 500 mg with each iron dose to enhance absorption, particularly critical in severe iron depletion. 1, 4
• If side effects occur, switch to every-other-day dosing, which increases fractional iron absorption and improves tolerance with similar efficacy. 1, 3

Alternative Oral Formulations

• Ferrous fumarate (106 mg elemental iron per 325 mg tablet) or ferrous gluconate (38 mg elemental iron per 325 mg tablet) are equally effective if ferrous sulfate is not tolerated, though typically more expensive. 1
• No single oral iron formulation has any therapeutic advantage over another—the choice is purely economic. 1

Expected Response and Monitoring

• Hemoglobin should rise by approximately 2 g/dL after 3-4 weeks of treatment. 1
• Check hemoglobin at 4 weeks; failure to rise by 2 g/dL indicates poor compliance, continued blood loss, or malabsorption. 1
• Continue oral iron for 3 months after hemoglobin normalizes to fully replenish iron stores. 1, 4
• Monitor hemoglobin and red cell indices every 3 months for the first year, then again after another year. 1

When to Switch to Intravenous Iron

Switch to IV iron if any of the following criteria are met: 1, 4

Absolute Indications

• Intolerance to at least two different oral iron preparations 1
• Failure of ferritin levels to improve after 4 weeks of compliant oral therapy 1
• Active inflammatory bowel disease with hemoglobin <10 g/dL (IV iron is first-line in this scenario) 1
• Post-bariatric surgery patients due to disrupted duodenal absorption mechanisms 1, 4
• Celiac disease with inadequate response to oral iron despite gluten-free diet adherence 1
• Ongoing gastrointestinal blood loss exceeding oral replacement capacity 1
• Second and third trimesters of pregnancy if oral iron fails 1, 4
• Chronic kidney disease with functional iron deficiency (ferritin 100-300 ng/mL with transferrin saturation <20%) 1
• Chronic heart failure with iron deficiency (ferritin <100 ng/mL or 100-300 ng/mL with transferrin saturation <20%) 1

IV Iron Formulation Selection

• Prefer IV iron formulations that can replace iron deficits with 1-2 infusions rather than multiple infusions. 1
• Ferric carboxymaltose (500-1000 mg single doses, delivered within 15 minutes) is a preferred formulation. 1
• Avoid iron dextran preparations due to higher risk of anaphylaxis requiring test doses. 1
• All IV iron formulations have similar overall safety profiles; true anaphylaxis is very rare (0.6-0.7%). 1
• Most reactions are complement activation-related pseudo-allergy (infusion reactions) that respond to slowing the infusion rate. 1

Special Population Considerations

Pregnant Women

• Start oral low-dose iron 30 mg/day at first prenatal visit for prevention. 1
• Treat anemia with 60-120 mg/day elemental iron. 1
• Refer for further evaluation if hemoglobin <9.0 g/dL. 1
• Use IV iron during second and third trimesters if oral iron fails or is not tolerated. 1, 4

Inflammatory Bowel Disease

• Treat active inflammation first to enhance iron absorption and reduce iron depletion. 1
• Use IV iron as first-line treatment when hemoglobin <10 g/dL with active inflammation. 1
• IV iron is more effective and better tolerated than oral iron in IBD patients (odds ratio 1.57 for achieving 2.0 g/dL hemoglobin increase). 1

Post-Bariatric Surgery

• IV iron is preferred due to anatomic considerations affecting duodenal absorption. 1, 4
• A single dose of IV iron is more effective and better tolerated than oral ferrous fumarate or ferrous gluconate. 1

Celiac Disease

• Ensure strict adherence to gluten-free diet to improve iron absorption. 1
• Screen with antiendomysial antibody and IgA measurement. 1
• Progress to IV iron if iron stores do not improve despite dietary compliance. 1

Critical Pitfalls to Avoid

• Do not prescribe multiple daily doses—this increases side effects without improving efficacy due to hepcidin-mediated absorption blockade. 1, 3
• Do not stop iron therapy when hemoglobin normalizes—continue for 3 months to replenish stores. 1
• Do not continue oral iron indefinitely without response—reassess after 4 weeks and switch to IV iron if hemoglobin fails to rise. 1
• Do not overlook vitamin C supplementation when oral iron response is suboptimal. 1
• Do not fail to identify and treat the underlying cause of iron deficiency while supplementing. 1, 5
• Do not delay IV iron therapy until anemia develops in patients with oral iron intolerance—iron deficiency itself causes symptoms that warrant treatment. 1

Failure to Respond

If anemia does not resolve within 6 months despite appropriate iron therapy: 1

• Reassess for ongoing blood loss 1
• Evaluate for malabsorption syndromes 1
• Consider further gastrointestinal investigation 1
• Verify patient adherence to therapy 1
• Consider hematology consultation for complex cases 1