First-Line Treatment for Iron Deficiency Anemia
Oral iron supplementation is the first-line treatment for iron deficiency anemia in most patients, specifically those with mild anemia, clinically inactive disease, and no prior intolerance to oral iron. 1
Treatment Algorithm Based on Clinical Context
Oral Iron as First-Line (Preferred Initial Therapy)
Use oral iron in patients meeting ALL of the following criteria: 1
- Mild anemia (hemoglobin 100-120 g/L in women, 100-130 g/L in men)
- Clinically inactive disease
- No previous intolerance to oral iron
- No ongoing active inflammation
Dosing: 100-200 mg elemental iron daily (ferrous sulfate 325 mg daily or alternate days) 2, 3
Intravenous Iron as First-Line (Preferred in Specific Situations)
Switch to IV iron as first-line when ANY of the following are present: 1
- Clinically active inflammatory bowel disease
- Previous intolerance to oral iron
- Hemoglobin below 100 g/L (10 g/dL)
- Need for erythropoiesis-stimulating agents
- Chronic kidney disease on dialysis
- Heart failure
- Malabsorption conditions (celiac disease, post-bariatric surgery, atrophic gastritis)
- Ongoing blood loss exceeding intestinal absorption capacity
- Second or third trimester of pregnancy
- Active cancer with iron deficiency anemia
Key Evidence: The European Crohn's and Colitis Organization guidelines conclude that IV iron is more effective, shows faster response, and is better tolerated than oral iron in inflammatory conditions. 1
Practical Considerations
Oral Iron Therapy
- Goal: Normalize hemoglobin levels and replenish iron stores 1
- Expected response: Hemoglobin increase of at least 2 g/dL within 4 weeks 1
- Duration: Often requires 3-6 months to achieve therapeutic goals 4
- Common pitfall: Gastrointestinal side effects reduce compliance; consider alternate-day dosing if side effects occur 2
Intravenous Iron Therapy
- Available formulations: Iron sucrose, ferric carboxymaltose, iron isomaltoside 1000 1
- Dosing estimation: Based on hemoglobin and body weight (see table below) 1
- Advantage: Rapidly achieves therapeutic targets without gastrointestinal complications 5, 3
Iron Dosing Table (for IV therapy)
| Hemoglobin (g/L) | Body weight <70 kg | Body weight ≥70 kg |
|---|---|---|
| 100-120 (women) / 100-130 (men) | 1000 mg | 1500 mg |
| 70-100 | 1500 mg | 2000 mg |
Monitoring and Re-treatment
- Re-treatment threshold: Initiate when serum ferritin drops below 100 μg/L or hemoglobin falls below 120 g/L (women) or 130 g/L (men) 1
- Monitoring frequency: Every 6-12 months in remission; every 3 months with active disease 1
Critical Diagnostic Context
Before initiating therapy, confirm iron deficiency: 1
- Without inflammation: Serum ferritin <30 μg/L
- With inflammation: Serum ferritin up to 100 μg/L may still indicate iron deficiency
- Transferrin saturation <20% supports diagnosis
The choice between oral and IV iron fundamentally depends on disease activity, severity of anemia, and patient-specific factors rather than a universal preference for one route over another. 1