Treatment of Iron Deficiency Anemia
Start with oral ferrous sulfate 200 mg once daily on an empty stomach, which is the preferred first-line treatment due to its effectiveness and low cost. 1
Initial Oral Iron Therapy
- Ferrous sulfate 200 mg once daily is the recommended formulation rather than multiple daily doses, as once-daily dosing improves tolerability while maintaining similar effectiveness 1
- Take iron 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 important when response is suboptimal 1
- Alternative oral formulations (ferrous gluconate or ferrous fumarate) are equally effective if ferrous sulfate is not tolerated 1
- Continue oral iron therapy for 3 months after anemia correction to fully replenish iron stores 1
Expected Response and Monitoring
- Hemoglobin should rise by approximately 2 g/dL after 3-4 weeks of treatment 1
- If no response occurs within 4 weeks, assess for non-adherence, malabsorption, or ongoing blood loss 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 be used as first-line treatment in specific clinical scenarios:
- Hemoglobin below 100 g/L (10 g/dL) 2
- Clinically active inflammatory bowel disease 2
- Intolerance to at least two different oral iron preparations 1
- Inadequate response to oral iron therapy after 4 weeks 1
- Conditions affecting iron absorption including inflammatory bowel disease with active inflammation, celiac disease with ongoing gluten exposure, or post-bariatric surgery 1
Intravenous Iron Formulations
- Prefer IV iron formulations that can replace iron deficits with 1-2 infusions 1
- Ferric carboxymaltose (500-1000 mg single doses, delivered within 15 minutes) is a preferred IV iron formulation 1
- Iron sucrose is indicated for iron deficiency anemia in patients with chronic kidney disease 3
- Avoid iron dextran preparations due to higher risk of anaphylaxis requiring test doses 1
Special Population Considerations
Inflammatory Bowel Disease
- IV iron is first-line treatment in patients with clinically active IBD and hemoglobin <100 g/L 2
- Oral iron may be used in patients with mild anemia whose disease is clinically inactive and who have not been previously intolerant to oral iron 2
- Treating underlying inflammation enhances iron absorption and reduces iron depletion 1
Post-Bariatric Surgery
- IV iron is preferred due to disrupted duodenal absorption mechanisms 1
Celiac Disease
- Ensure strict adherence to gluten-free diet to improve iron absorption 1
- Consider IV iron therapy if iron stores do not improve with oral supplementation despite dietary compliance 1
Identifying Underlying Cause
- In premenopausal women, assess menstrual blood loss first, as menorrhagia is responsible for iron deficiency in 5-10% of menstruating women 1
- In men and postmenopausal women, perform gastrointestinal evaluation with upper endoscopy and colonoscopy 1
- Screen for celiac disease with antiendomysial antibody and IgA measurement, particularly in younger patients 1
Common Pitfalls to Avoid
- Do not prescribe multiple daily doses of oral iron - this increases side effects without improving efficacy 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 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