What type of iron supplementation do you recommend for patients with iron deficiency anemia and when should it be given?

Iron Supplementation for Iron Deficiency Anemia

Ferrous sulfate is the preferred oral iron formulation for iron deficiency anemia, administered once daily rather than multiple times per day, with vitamin C to enhance absorption. Intravenous iron should be used when oral iron is not tolerated, ineffective, or contraindicated. 1

Oral Iron Therapy: First-Line Approach

Preferred Formulation and Dosing

• Formulation: Ferrous sulfate is recommended as the least expensive and equally effective iron formulation 1
• Dosing frequency: Once daily dosing is preferred over multiple daily doses 1
  • Every-other-day dosing may be better tolerated with similar absorption rates
  • Traditional three-times-daily dosing is no longer recommended
• Standard dose: 200 mg ferrous sulfate (providing approximately 65 mg elemental iron) once daily 1
• Administration: Take with 80 mg vitamin C (e.g., orange juice) to enhance absorption 1, 2
• Duration: Continue for three months after correction of anemia to replenish iron stores 1

Optimizing Oral Iron Therapy

• Avoid taking with tea, coffee, or calcium-containing foods (interfere with absorption)
• Take on an empty stomach if tolerated; if GI side effects occur, can take with food
• Common side effects include constipation, diarrhea, and nausea
• Monitor hemoglobin response within 2-4 weeks of starting therapy 2

When to Use Intravenous Iron

Intravenous iron is indicated in the following situations 1, 2:

1. Intolerance to at least two oral iron preparations
2. Poor compliance with oral therapy
3. Failure to respond to oral iron (ferritin levels not improving)
4. Conditions where oral iron is unlikely to be absorbed:
   • Inflammatory bowel disease with active inflammation
   • After bariatric surgery procedures
   • Chronic kidney disease
5. Need for rapid correction of severe anemia
6. Ongoing blood loss exceeding the capacity of oral replacement

IV Iron Formulation Selection

• Prefer IV iron formulations that can replace iron deficits with 1-2 infusions 1
• Ferric carboxymaltose (Injectafer) can deliver complete iron repletion in just two administrations (typically 750 mg × 2 doses 7 days apart) 2
• Iron sucrose (Venofer) is another option, particularly for patients with chronic kidney disease 3

IV Iron Dosing

Dosing based on hemoglobin and body weight 2:

• For hemoglobin 100-120 g/L (women) or 100-130 g/L (men):
  • <70 kg: 1000 mg total
  • ≥70 kg: 1500 mg total
• For hemoglobin 70-100 g/L:
  • <70 kg: 1500 mg total
  • ≥70 kg: 2000 mg total

Special Populations

Inflammatory Bowel Disease

• Determine whether iron deficiency is due to inadequate intake/absorption or blood loss 1
• Treat active inflammation to enhance iron absorption
• Use IV iron in patients with active inflammation and compromised absorption 1, 2

Portal Hypertensive Gastropathy

• Start with oral iron supplements initially
• Switch to IV iron therapy in patients with ongoing bleeding who don't respond to oral iron 1

Monitoring and Follow-up

• Check hemoglobin response after 3-4 weeks of therapy (should rise by approximately 2 g/dL) 1
• Complete follow-up iron studies after 8-10 weeks of treatment 2
• Once normal, monitor hemoglobin and red cell indices at 3-month intervals for one year, then after another year 1
• Provide additional iron if hemoglobin or MCV falls below normal
• Further investigation is only necessary if hemoglobin and MCV cannot be maintained with supplementation 1

Common Pitfalls to Avoid

1. Using multiple daily doses of oral iron, which increases side effects without improving efficacy
2. Failing to add vitamin C to enhance iron absorption
3. Not continuing iron therapy long enough to replenish stores (stopping once hemoglobin normalizes)
4. Delaying transition to IV iron when oral therapy is failing
5. Checking ferritin levels too early after IV iron administration (will be falsely elevated)
6. Overlooking the underlying cause of iron deficiency while treating the anemia

Remember that failure to respond to appropriate iron therapy should prompt reassessment for ongoing blood loss, malabsorption, or incorrect diagnosis.