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

Treatment of Iron Deficiency

Start oral ferrous sulfate 200 mg once daily immediately—this is the preferred first-line treatment for iron deficiency with or without anemia. 1

Initial Oral Iron Therapy

Ferrous sulfate 200 mg (containing 65 mg elemental iron) taken once daily is the gold standard treatment due to its superior cost-effectiveness, with no therapeutic advantage of any other oral iron formulation. 1

Key Dosing Principles

• Once-daily dosing is superior to multiple daily doses—it improves gastrointestinal tolerance while maintaining equal or better iron absorption due to hepcidin regulation that blocks further absorption for 48 hours after iron intake. 1, 2
• 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 when iron saturation is severely low. 1
• Alternative formulations (ferrous fumarate 106 mg elemental iron 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

Expected Response and Monitoring

• Hemoglobin should rise by approximately 2 g/dL after 3-4 weeks of treatment. 3, 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
• 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

Intravenous iron should replace oral therapy in specific clinical scenarios where oral iron is inadequate or contraindicated. 1, 4

Absolute Indications for IV Iron

• Intolerance to at least two different oral iron preparations (ferrous sulfate, ferrous fumarate, or ferrous gluconate). 3, 1
• Active inflammatory bowel disease with hemoglobin <100 g/L (10 g/dL)—IV iron is first-line treatment in this setting. 3
• Post-bariatric surgery patients due to disrupted duodenal absorption mechanisms. 1
• Celiac disease with inadequate response to oral iron despite strict adherence to gluten-free diet. 1
• Ongoing gastrointestinal blood loss exceeding oral replacement capacity. 1
• Pregnancy during second and third trimesters when oral iron is insufficient. 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 Formulations

• Prefer IV iron preparations that replace iron deficits in 1-2 infusions rather than multiple infusions to minimize risk of anaphylaxis and infusion reactions. 1
• Ferric carboxymaltose (500-1000 mg single doses, delivered within 15 minutes) is a preferred formulation. 1
• Iron sucrose requires multiple visits with maximum 200 mg per infusion over 10 minutes. 5
• Ferric gluconate is dosed at 125 mg per dialysis session for hemodialysis patients. 6
• All IV iron formulations have similar overall safety profiles—true anaphylaxis is very rare (0.6-0.7%), with most reactions being complement activation-related pseudo-allergy that responds to slowing the infusion rate. 1

Special Population Considerations

Inflammatory Bowel Disease

• Oral iron should be considered first-line only in patients with mild anemia, clinically inactive disease, and no previous intolerance to oral iron. 3
• IV iron is first-line when hemoglobin is below 100 g/L with clinically active IBD. 3
• Treat active inflammation effectively to enhance iron absorption and reduce iron depletion. 1
• After successful IV iron treatment, re-treatment should be initiated when serum ferritin drops below 100 mg/L or hemoglobin falls below 12-13 g/dL according to gender. 3

Pregnancy

• 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 pregnant women with hemoglobin <9.0 g/dL for further medical evaluation. 1
• IV iron is indicated during second and third trimesters if oral iron is insufficient. 1, 4

Post-Bariatric Surgery

• IV iron is the preferred treatment option due to disrupted duodenal absorption mechanisms from anatomic changes. 1

Celiac Disease

• Ensure strict adherence to gluten-free diet to improve iron absorption. 1
• Start with oral iron supplementation initially. 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 of oral iron—this increases gastrointestinal side effects without improving efficacy due to hepcidin-mediated absorption blockade. 1
• 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 by 2 g/dL. 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
• 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:

• 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