Should a patient with low ferritin (iron deficiency) levels receive oral iron or intravenous (IV) iron therapy?

Management of Iron Deficiency with Ferritin of 13

For a patient with a ferritin level of 13 ng/mL, oral iron supplementation should be initiated as first-line therapy, using ferrous sulfate 65 mg elemental iron once daily in the morning on alternate days with vitamin C to maximize absorption.

Assessment of Iron Deficiency

A ferritin level of 13 ng/mL indicates absolute iron deficiency, as it falls well below the diagnostic threshold of 100 ng/mL 1. This low ferritin level represents depleted iron stores that require replenishment to prevent or treat anemia and associated symptoms.

Key diagnostic considerations:

• Ferritin <100 ng/mL indicates absolute iron deficiency 1
• Transferrin saturation should also be assessed (likely <20% with such low ferritin)
• Hemoglobin levels determine if iron deficiency has progressed to anemia

Treatment Algorithm

1. First-line therapy: Oral Iron

• Recommended formulation: Ferrous sulfate 65 mg elemental iron 1
• Dosing schedule: Once daily in the morning on alternate days
• Administration: Take on an empty stomach with 80 mg vitamin C (improves absorption) 1
• Duration: Continue for at least 3 months to replenish iron stores

2. Monitoring response:

• Assess hemoglobin after 2 weeks (should increase by 1 g/dL if anemic) 1
• Check ferritin after 1 month (should show significant increase) 1
• If no improvement in these parameters despite adherence, switch to IV iron

3. When to consider IV iron instead:

• Intolerance to oral iron (gastrointestinal side effects)
• Failure to respond to oral iron despite adherence
• Conditions with impaired absorption:
  • Active inflammatory bowel disease
  • Post-bariatric surgery
  • When iron loss exceeds oral absorption capacity 1

Optimizing Oral Iron Therapy

Maximizing absorption:

• Morning dosing is preferred (circadian hepcidin levels are lower) 2
• Alternate-day dosing improves absorption (hepcidin levels remain elevated for up to 48 hours after dosing) 1, 2
• Take with vitamin C (forms chelate with iron, prevents formation of insoluble compounds) 1

Minimizing side effects:

• Avoid taking with tea or coffee (powerful inhibitors of iron absorption) 1
• Take at least 1 hour before meals containing calcium or fiber
• If GI side effects occur, consider:
  • Reducing dose
  • Switching to alternate-day dosing if not already implemented
  • Trying a different iron formulation (ferrous gluconate or ferrous bisglycinate)

Common Pitfalls to Avoid

1. Overdosing: Taking iron more than once daily does not improve absorption but increases side effects 1

2. Poor timing: Consuming tea, coffee, calcium, or fiber within an hour of iron supplementation reduces absorption 1

3. Inadequate duration: Iron therapy should continue for 3 months after hemoglobin normalization to replenish stores

4. Missing underlying causes: Always investigate the cause of iron deficiency (e.g., blood loss, malabsorption)

5. Delayed switch to IV iron: If oral iron is ineffective after 1 month of proper use, IV iron should be considered 1

While IV iron formulations like ferric carboxymaltose 3 and iron sucrose 4 are effective alternatives, they are substantially more expensive than oral formulations and should be reserved for specific indications as outlined above 1.