How is iron deficiency treated?

Treatment of Iron Deficiency

Oral iron supplementation with ferrous sulfate 65 mg elemental iron daily should be the first-line treatment for most patients with iron deficiency, while intravenous iron is indicated for specific patient populations with poor tolerance or response to oral therapy. 1

Diagnosis of Iron Deficiency

Before initiating treatment, proper diagnosis is essential:

• Serum ferritin is the most sensitive diagnostic test:
  • <30 μg/L: Definitive iron deficiency
  • 30-100 μg/L with transferrin saturation <20%: Possible iron deficiency, especially with inflammation

  • 100 μg/L with normal transferrin saturation: Iron deficiency unlikely 1

• In patients with inflammation, chronic disease, or malignancy, use a higher ferritin cutoff (<100 μg/L) 1
• Transferrin saturation <16% supports diagnosis of iron deficiency 1
• Therapeutic response (Hb increase ≥1 g/dL after 4 weeks) confirms diagnosis 1

Treatment Algorithm

First-Line Treatment: Oral Iron

• Standard dosing: Ferrous sulfate 65 mg elemental iron daily between meals to maximize absorption 1
• Expected response: Hemoglobin increase of ≥1 g/dL within 4 weeks 1
• Duration: Continue for 3 months after normalization of hemoglobin to replenish iron stores 1
• Alternative dosing strategy: Consider alternate-day dosing (60-120 mg elemental iron) in the morning to improve absorption and reduce side effects 2, 3

Indications for Intravenous Iron

Switch to IV iron therapy when:

1. Intolerance to oral iron (gastrointestinal side effects) 1, 4
2. Unsatisfactory response to oral iron despite compliance 1, 4
3. Clinically active inflammatory bowel disease 1
4. Heart failure with iron deficiency (NYHA class II/III) 1, 4
5. Need for rapid iron repletion 5
6. Non-dialysis dependent chronic kidney disease 4, 6

IV Iron Options

1. Ferric Carboxymaltose (Injectafer):

   • For patients ≥50 kg: 750 mg IV in two doses separated by ≥7 days (total 1,500 mg) 4
   • For patients <50 kg: 15 mg/kg IV in two doses separated by ≥7 days 4
   • Alternative: 15 mg/kg up to 1,000 mg as a single dose 4
   • For heart failure patients: Dosing based on weight and hemoglobin (see Table 1 in drug label) 4

2. Iron Sucrose (Venofer):

   • For non-dialysis CKD: 200 mg IV on 5 occasions over 14 days (total 1,000 mg) 6
   • For hemodialysis patients: 100 mg IV per dialysis session 6

Special Considerations

Gastrointestinal Evaluation

• Upper GI endoscopy with small bowel biopsies should be performed to rule out celiac disease 1
• Lower GI evaluation (colonoscopy) should be performed unless upper GI endoscopy reveals carcinoma or celiac disease 1
• Testing for H. pylori should be considered 1

Monitoring Response

• Check hemoglobin levels within 4 weeks of starting iron therapy 1
• If no response is seen despite compliance, further evaluation is needed 1
• Target transferrin saturation should be >20% to ensure adequate iron stores 1

Common Pitfalls to Avoid

1. Failure to identify underlying cause: Particularly important in men and postmenopausal women where gastrointestinal malignancy must be excluded 1
2. Using inappropriate ferritin cutoffs: Adjust cutoffs in patients with inflammation 1
3. Relying solely on hemoglobin for diagnosis: Include iron studies 1
4. Mistaking infusion reactions for true anaphylaxis: Most reactions to IV iron are complement activation-related pseudo-allergy 1
5. Continuing oral iron despite poor response: Consider switching to IV iron if no response after 4 weeks 1

Follow-up and Prevention

• Continue iron supplementation for 3 months after hemoglobin normalization 1
• For IV iron, re-treatment should be initiated when serum ferritin drops below 100 μg/L 1
• Encourage consumption of iron-rich foods 1
• Screen high-risk populations for iron deficiency, including pregnant women, young children, and heart failure patients 1

Iron deficiency often recurs after successful treatment, requiring ongoing monitoring to prevent recurrence 1.