What is the first line of treatment for anemia in an active patient with Crohn's (Chronic Regional Ileitis) disease?

First-Line Treatment for Anemia in Active Crohn's Disease

Intravenous iron should be considered as first-line treatment for anemia in patients with active Crohn's disease. 1

Diagnosis of Anemia in Crohn's Disease

Anemia is the most frequent extraintestinal manifestation of inflammatory bowel disease (IBD), including Crohn's disease. Before initiating treatment, proper diagnosis is essential:

• The major forms of anemia in IBD are iron deficiency anemia, anemia of chronic disease, and anemia of mixed origin 1
• Diagnostic criteria depend on the level of inflammation:
  • Without inflammation: serum ferritin <30 μg/L indicates iron deficiency 1
  • With inflammation: serum ferritin up to 100 μg/L may still be consistent with iron deficiency 1
  • Transferrin saturation <20% with ferritin >100 μg/L suggests anemia of chronic disease 1
  • Ferritin between 30-100 μg/L with inflammation likely indicates a combination of iron deficiency and anemia of chronic disease 1

Treatment Algorithm for Anemia in Active Crohn's Disease

Step 1: Assess Disease Activity and Anemia Severity

• Determine if Crohn's disease is active (based on clinical, endoscopic, or biochemical evidence)
• Measure hemoglobin level to classify anemia severity:
  • Mild: Hb 100-120 g/L (women) or 100-130 g/L (men)
  • Moderate-severe: Hb <100 g/L

Step 2: Select Treatment Based on Disease Activity and Anemia Severity

For patients with active Crohn's disease:

• Use intravenous iron as first-line treatment 1, 2
• This applies especially to:
  • Patients with moderate-severe anemia (Hb <100 g/L)
  • Those with previous intolerance to oral iron
  • Patients requiring erythropoiesis-stimulating agents 1

For patients with inactive Crohn's disease:

• Consider oral iron for mild anemia if no previous intolerance to oral iron 1
• Use intravenous iron if oral iron is not tolerated or ineffective 1

Dosing of IV Iron

The required iron dose should be calculated based on baseline hemoglobin and body weight:

Hemoglobin g/L	Body weight <70 kg	Body weight ≥70 kg
100-120 (women) or 100-130 (men)	1000 mg	1500 mg
70-100	1500 mg	2000 mg

1, 3

Rationale for IV Iron in Active Crohn's Disease

1. Impaired oral absorption: Patients with active Crohn's disease have impaired oral iron absorption that correlates with disease activity and inflammatory markers 4

2. Better efficacy: IV iron demonstrates higher efficacy in achieving a hemoglobin rise of 2.0 g/dL compared to oral iron 1

3. Fewer gastrointestinal side effects: Treatment discontinuation rates due to adverse events are lower with IV iron compared to oral iron 1

4. Avoidance of disease exacerbation: Oral iron may potentially exacerbate intestinal inflammation through the generation of reactive oxygen species 1

5. Safety profile: Despite previous concerns, modern IV iron formulations have a favorable safety profile with very rare serious adverse events (only 1.3% of IBD patients experience any adverse reaction) 5

Monitoring and Follow-up

After successful treatment with IV iron:

• Re-treatment should be initiated as soon as serum ferritin drops below 100 μg/L or hemoglobin falls below 120 g/L (women) or 130 g/L (men) 1, 3
• Monitor hemoglobin levels and iron parameters (ferritin, transferrin saturation) 4-8 weeks after treatment 3
• Long-term monitoring is warranted as recurrence of anemia is common (>50% after 1 year) 1

Special Considerations

• Erythropoietic therapy: Should be considered when anemia does not improve despite IV iron therapy and control of inflammation 1
• Blood transfusion: Should be restricted to special clinical situations such as acute severe anemia with hemodynamic instability or failure of other treatments 1
• Underlying disease control: Treating the underlying Crohn's disease is an important step in managing anemia, though this alone is rarely sufficient to normalize hemoglobin levels 1

Common Pitfalls to Avoid

• Misinterpreting iron studies during inflammation (ferritin may be falsely elevated)
• Inadequate dosing or premature discontinuation of iron therapy
• Failing to monitor for recurrence of anemia after successful treatment
• Using oral iron in patients with active disease, which may be both ineffective and potentially harmful