What is the correct dose for iron supplementation in adults with iron deficiency anemia?

Correct Dosing for Iron Supplementation in Adults with Iron Deficiency Anemia

For adults with iron deficiency anemia, the recommended dose is 50-100 mg of elemental iron once daily, taken in the fasting state. 1, 2

Initial Dosing Recommendations

• Ferrous sulfate 200 mg tablet (containing 65 mg elemental iron) once daily is the most cost-effective and widely recommended option 1, 2, 3
• Iron should be taken on an empty stomach to maximize absorption, as food can reduce absorption by up to 50% 2
• Monitoring hemoglobin after 2 weeks of treatment is essential to assess response - absence of a 10 g/L rise strongly predicts treatment failure (sensitivity 90.1%, specificity 79.3%) 1

Alternative Dosing Strategies

• For patients experiencing gastrointestinal side effects, alternate-day dosing (one tablet every other day) can be considered while maintaining efficacy 1, 4
• Morning dosing is preferred over afternoon or evening administration due to circadian variations in hepcidin levels that affect iron absorption 4
• Ferrous gluconate (324 mg tablet providing 38 mg elemental iron) is an alternative for those who cannot tolerate ferrous sulfate 5

Duration of Treatment

• After normalization of hemoglobin, treatment should continue for 2-3 months to replenish iron stores 1, 2, 6
• Regular monitoring is recommended with blood count checks every 3 months for the first year, then every 6 months for 2-3 years 1, 2

Managing Side Effects

• Gastrointestinal adverse effects (nausea, diarrhea, constipation) are common with oral iron preparations 1
• Side effects are significantly more common with ferrous sulfate than with placebo (OR 2.32) or parenteral iron (OR 3.05) 1
• There is no dose-effect relationship for side effects in the range of 50-400 mg elemental iron per day 1

When to Consider Parenteral Iron

• Consider parenteral iron for patients with:
  • Significant intolerance to oral iron therapy 1
  • Chronic disease with ongoing blood loss 1
  • Impaired absorption or GI inflammatory pathology 1
  • Need for rapid correction of severe anemia 2

Common Pitfalls to Avoid

• Switching between different traditional iron salts when side effects occur is not supported by evidence 1
• Taking iron with food significantly reduces absorption but is sometimes necessary if GI side effects are severe 2
• Failure to monitor response may miss non-responders who need alternative approaches 1, 2
• Discontinuing treatment once hemoglobin normalizes without completing the full course needed to replenish iron stores 2, 6