How to manage a patient with iron deficiency anemia?

Management of Iron Deficiency Anemia

Start with oral ferrous sulfate 200 mg once daily, which is the preferred first-line treatment due to its effectiveness and low cost. 1, 2

Initial Oral Iron Therapy

• Ferrous sulfate 200 mg once daily is the standard first-line treatment, providing 65 mg of elemental iron per dose. 1, 2, 3
• Once-daily dosing is superior to multiple daily doses because it improves tolerability while maintaining equivalent effectiveness. 2
• Take iron on an empty stomach for optimal absorption, though taking with food is acceptable if gastrointestinal side effects occur. 2
• Add ascorbic acid (vitamin C) 250-500 mg twice daily with the iron preparation to enhance absorption, particularly when response is poor. 1, 2
• Alternative oral formulations (ferrous gluconate or ferrous fumarate) are equally effective if ferrous sulfate is not tolerated. 1, 2
• Continue oral iron therapy for 3 months after hemoglobin normalizes to fully replenish iron stores. 1, 2

Expected Response and Monitoring

• Hemoglobin should rise by approximately 2 g/dL after 3-4 weeks of treatment. 1, 2
• If no response occurs within 4 weeks, assess for non-adherence, ongoing blood loss, malabsorption, or misdiagnosis. 1, 2
• Monitor hemoglobin and red cell indices every 3 months for the first year, then again after another year, and subsequently if symptoms develop. 1, 2
• Provide additional iron supplementation if hemoglobin or red cell indices fall below normal during follow-up. 1, 2

When to Switch to Intravenous Iron

Intravenous iron is indicated when oral iron fails or specific conditions exist that impair absorption or require rapid repletion. 1, 2

Absolute Indications for IV Iron:

• Intolerance to at least two different oral iron preparations. 1, 2
• Inflammatory bowel disease with active inflammation, especially if hemoglobin <10 g/dL. 1, 2
• Post-bariatric surgery patients due to disrupted duodenal iron absorption. 2, 4
• Celiac disease with inadequate response to oral iron despite strict gluten-free diet adherence. 1, 2
• Ongoing gastrointestinal blood loss exceeding oral replacement capacity. 2
• Second and third trimesters of pregnancy when oral iron is insufficient. 2, 4
• Chronic kidney disease, heart failure, or cancer with chronic inflammation. 4

IV Iron Formulation Selection:

• Prefer ferric carboxymaltose (1000 mg single dose over 15 minutes) or iron sucrose (200 mg over 10 minutes) for convenience and safety. 1, 2
• Avoid iron dextran when possible due to higher risk of anaphylaxis (0.6-0.7% serious reactions). 1, 2
• Resuscitation facilities must be available when administering any intravenous iron preparation. 1

Investigation of Underlying Cause

All patients (except menstruating women without other risk factors) require investigation to identify the source of iron loss. 1

Mandatory Initial Testing:

• Screen all patients for celiac disease with tissue transglutaminase antibody (IgA type) and total IgA measurement. 1, 2

Bidirectional Endoscopy Indications:

• All men and postmenopausal women require both upper endoscopy with small bowel biopsy and colonoscopy (or CT colonography). 1
• Premenopausal women aged ≥50 years require full gastrointestinal investigation. 1
• Premenopausal women <50 years require upper endoscopy only if they have upper GI symptoms, family history of colorectal cancer, or persistent anemia after iron supplementation. 1, 2

Special Population Considerations:

Post-gastrectomy patients aged >50 years: Investigate despite surgical history due to 2-3 fold increased risk of gastric and colon cancer after 20 years. 1

Patients on warfarin or aspirin: Do not attribute iron deficiency to these medications until full GI investigation is completed. 1

Patients on proton pump inhibitors: Do not consider these patients less likely to have malignancy; investigate fully. 1

Pregnant women: Reserve colonoscopy for very strong indications; prefer MR colonography over radiological imaging (avoid MRI in first trimester). 1

Treatment of Specific Underlying Conditions

Celiac Disease:

• Initiate strict gluten-free diet, which may correct anemia without iron supplementation in mild cases. 1
• Add oral iron if symptoms are present or histologic abnormalities are mild. 1
• Use IV iron for severe villous atrophy or if oral iron fails after 3-6 months of gluten-free diet. 1
• Up to 20% remain iron deficient despite strict gluten avoidance and require ongoing supplementation. 1

Gastric Antral Vascular Ectasia (GAVE):

• Treat with endoscopic band ligation (preferred) or thermal ablation (argon plasma coagulation/radiofrequency ablation). 1
• Endoscopic band ligation requires fewer sessions (mean 2.63 vs 3.83) and produces greater hemoglobin improvement (0.59 g/dL difference). 1
• Provide iron repletion (oral or IV depending on severity) alongside endoscopic therapy. 1

Portal Hypertensive Gastropathy:

• Manage portal hypertension with beta-blockers or transjugular intrahepatic portosystemic shunt. 1
• Start with oral iron (no malabsorptive defect exists), but IV iron is reasonable for profound anemia. 1

Inflammatory Bowel Disease:

• IV iron is first-line treatment when hemoglobin <10 g/dL with clinically active disease. 2
• Treat underlying inflammation to enhance iron absorption and reduce depletion. 2

Common Pitfalls to Avoid

• Do not prescribe multiple daily doses of oral iron - this increases side effects without improving efficacy. 2
• Do not stop iron therapy when hemoglobin normalizes - continue for 3 months to replenish stores. 1, 2
• Do not continue oral iron indefinitely without response - reassess after 4 weeks and switch to IV iron if hemoglobin fails to rise. 2
• Do not overlook vitamin C supplementation when oral iron response is suboptimal. 1, 2
• Do not fail to identify and treat the underlying cause while supplementing iron. 2
• Do not attribute iron deficiency to warfarin, aspirin, or proton pump inhibitors without completing full investigation. 1

Failure to Respond to Treatment

If anemia does not resolve within 6 months despite appropriate iron therapy, take the following steps: 1, 2

• Reassess for ongoing blood loss (repeat endoscopy if indicated). 2
• Evaluate for malabsorption syndromes (consider capsule endoscopy or enterography if bidirectional endoscopy was negative and red flags exist). 5
• Verify patient adherence to therapy. 2
• Consider hematology consultation for complex cases. 2
• Investigate for other causes of anemia (anemia of chronic disease, combined deficiencies). 2