Treatment of Iron Deficiency Anemia
Start with oral iron supplementation at 50-100 mg elemental iron once daily on an empty stomach, and if hemoglobin fails to rise by at least 1.0 g/dL (10 g/L) at 2 weeks, transition to intravenous iron. 1
Initial Oral Iron Therapy
Prescribe ferrous sulfate 325 mg (65 mg elemental iron) once daily in the fasting state as first-line treatment for uncomplicated IDA, as this represents the simplest and least expensive option. 1, 2
Dosing Strategies
Standard daily dosing: 50-100 mg elemental iron once daily produces optimal balance between efficacy and tolerability. 1
Alternate-day dosing: Consider giving 60-120 mg elemental iron every other day rather than daily, as this produces similar hemoglobin increments with significantly lower nausea rates, though with slower initial response. 1, 3 This approach maximizes fractional iron absorption because oral iron doses ≥60 mg stimulate hepcidin elevation that persists 24 hours but subsides by 48 hours. 3
Timing: Administer iron in the morning only, not in afternoon or evening, as the circadian increase in plasma hepcidin is augmented by morning iron doses. 3
Alternative Oral Formulations
- Ferric maltol 30 mg twice daily is better tolerated than traditional ferrous salts but more expensive and slower to replenish stores, normalizing hemoglobin in 63-66% at 2 weeks and 89% at 1 year. 1
Monitoring Response
Check hemoglobin at 2 weeks: Absence of at least 1.0 g/dL (10 g/L) rise predicts subsequent treatment failure with 90.1% sensitivity and 79.3% specificity. 1, 4
Recheck hemoglobin every 4 weeks until normalized. 1
Continue oral iron for 2-3 months after hemoglobin normalization to replenish iron stores. 1
Typical response shows hemoglobin improvement within 1 month of oral therapy. 1
Intravenous Iron Therapy
Reserve IV iron for patients with:
- Intolerance to oral iron 1
- Malabsorption (post-bariatric surgery, celiac disease) 5, 1
- Ongoing blood loss exceeding oral replacement capacity 1, 6
- Inflammatory conditions (IBD, chronic heart failure, chronic kidney disease) 1
- Failure to respond to oral iron at 2 weeks 4
IV Iron Formulations
Ferric carboxymaltose and ferric derisomaltose are suitable first-line IV options. 1
Iron sucrose can be administered as 200 mg over 10 minutes, with multiple doses potentially required based on severity. 6
IV iron produces clinically meaningful hemoglobin response within 1 week and is more effective than oral therapy in chronic disease, continuing blood loss, impaired absorption, or GI inflammatory pathology. 1
Resuscitation facilities should be available during administration as a precaution. 6
Special Population Considerations
Inflammatory Bowel Disease
Use IV iron as first-line therapy for IBD patients with hemoglobin <10 g/dL, as recommended by the European Crohn's and Colitis Organization. 5
IV iron has greater efficacy than oral iron in achieving hemoglobin increase of 2.0 g/dL (OR 1.57; 95% CI 1.13-2.18) and is better tolerated with lower discontinuation rates (OR 0.27; 95% CI 0.13-0.59). 5
Oral iron may be appropriate only in carefully selected IBD patients with mild anemia, clinically inactive disease, and demonstrated tolerance, requiring close follow-up. 5
Treatment must first address underlying inflammation to control ulceration and chronic blood loss. 5
Post-Bariatric Surgery
Prefer IV iron in post-bariatric surgery patients, particularly in severe cases or when oral supplementation is ineffective. 5
A single dose of IV iron is more effective and better tolerated than oral ferrous fumarate or ferrous gluconate in women after Roux-en-Y gastric bypass. 5
Perform esophagogastroduodenoscopy to exclude anastomotic ulcer disease causing chronic bleeding. 5
Portal Hypertensive Gastropathy
Oral iron therapy is sufficient for PHG patients as there is no known malabsorptive defect, though IV iron is reasonable in those with severe iron depletion. 5
- Address underlying cirrhosis and portal hypertension with nonselective β-blockers, transjugular intrahepatic portosystemic shunts, or liver transplantation. 5
Chronic Heart Failure
IV iron improves symptoms, quality of life, and exercise capacity in chronic heart failure patients with iron deficiency, even without anemia. 1
Chronic Kidney Disease
Functional iron deficiency is common in CKD patients, and IV iron formulations are specifically approved for this indication. 1
Blood Transfusion
Reserve transfusion only for severe symptomatic anemia with circulatory compromise, targeting hemoglobin 70-90 g/L. 1
Consider parenteral iron as an alternative before transfusion, as each unit of blood contains only ~200 mg elemental iron, insufficient to replenish stores in severe IDA. 1
Always follow transfusion with iron replacement therapy. 1
Common Pitfalls
Avoid afternoon or evening dosing after a morning dose, as this reduces absorption due to hepcidin elevation. 3
Do not prescribe divided daily doses of high-dose iron (>60 mg), as this reduces fractional absorption and increases side effects. 3
Do not continue oral iron beyond 2 weeks without documented hemoglobin response, as this delays appropriate transition to IV therapy. 4
Do not use oral iron as first-line in active IBD with hemoglobin <10 g/dL, as IV iron is superior. 5