What is the recommended dosage of elemental iron for adults with iron deficiency anemia?

Recommended Dosage of Elemental Iron for Adults with Iron Deficiency Anemia

For adults with iron deficiency anemia, the recommended oral dosage is 50-100 mg of elemental iron once daily, taken in the fasting state. 1

Initial Oral Iron Therapy

• Ferrous sulfate 200 mg tablet (containing 65 mg elemental iron) once daily is a cost-effective first-line option 1, 2
• Alternative iron salts include:
  • Ferrous fumarate tablets (69-106 mg elemental iron per tablet) 1
  • Ferrous gluconate tablets (37-38 mg elemental iron per tablet) 1, 3
• Morning administration is preferable to maximize absorption 4
• Take on an empty stomach for optimal absorption, although this may increase gastrointestinal side effects 1

Monitoring Response

• Check hemoglobin after 2-4 weeks of therapy to assess initial response 1
• An increase in hemoglobin of at least 10 g/L after 2 weeks strongly predicts successful treatment (sensitivity 90.1%, specificity 79.3%) 1
• Continue monitoring hemoglobin every 4 weeks until normalized 1
• After normalization of hemoglobin, continue iron therapy for 2-3 months to replenish iron stores 1

Alternative Dosing Strategies

• For patients experiencing gastrointestinal side effects:
  • Consider alternate-day dosing (e.g., 100-120 mg elemental iron every other day) 1, 4
  • This approach may reduce side effects while maintaining similar efficacy 4, 5
• For elderly patients (>80 years), lower doses (15-50 mg elemental iron daily) may be equally effective with fewer side effects 6

When to Consider Parenteral Iron

• Parenteral iron should be used when oral iron is: 1
  • Contraindicated
  • Ineffective (no hemoglobin response after 2-4 weeks)
  • Not tolerated due to side effects
• Specific conditions where parenteral iron may be preferred: 5
  • Severe anemia requiring rapid correction
  • Chronic inflammatory conditions (IBD, CKD, heart failure)
  • Ongoing blood loss
  • Malabsorption (e.g., celiac disease, post-bariatric surgery)

Common Pitfalls and Caveats

• Modified-release iron preparations are not recommended as they release iron beyond the duodenum where absorption is poor 1
• Switching between different iron salts when side effects occur is not supported by evidence 1
• Multivitamins typically contain insufficient iron (up to 14 mg) for treating iron deficiency anemia 1
• Blood transfusion should be reserved for severe symptomatic anemia or circulatory compromise, and should always be followed by adequate iron replacement 1
• Dividing the daily dose does not improve absorption and may increase side effects due to hepcidin stimulation 1, 4

By following these dosing recommendations and monitoring protocols, most patients with iron deficiency anemia should achieve normalization of hemoglobin levels and replenishment of iron stores, leading to resolution of symptoms and improved quality of life.