Recommended Dosage of Elemental Iron for Iron Deficiency Anemia
The recommended dosage of elemental iron for patients with iron deficiency anemia is 50-100 mg of elemental iron once daily. 1, 2
Iron Formulations and Elemental Iron Content
Different iron salt preparations contain varying amounts of elemental iron:
| Iron Preparation | Tablet Size | Elemental Iron Content |
|---|---|---|
| Ferrous sulfate | 325 mg | 65 mg |
| Ferrous fumarate | 325 mg | 106 mg |
| Ferrous gluconate | 324 mg | 38 mg |
Dosing Recommendations by Patient Population
General Adult Population
- Initial therapy: Start with 50-100 mg of elemental iron once daily 1
- This typically corresponds to one 325 mg ferrous sulfate tablet daily
Specific Conditions
- Inflammatory Bowel Disease: No more than 100 mg elemental iron per day 1
- Chronic Kidney Disease: 200 mg elemental iron daily, divided into 2-3 doses 1
- Menometrorrhagia: 60-120 mg elemental iron daily depending on severity 5
Optimizing Iron Absorption
Recent evidence suggests that iron absorption may be improved by:
- Timing: Morning administration is preferable as the circadian increase in plasma hepcidin is augmented by a morning iron dose 6, 7
- Frequency: Alternate-day dosing may increase fractional iron absorption compared to consecutive-day dosing 6, 7
- Empty stomach: Iron is best absorbed when taken without food or other medications 1
- Avoid calcium-containing foods/supplements: These can reduce iron absorption
Monitoring Response to Treatment
- Assess adequacy of response after 1 month (hemoglobin rise of ≥1.0 g/dL, normalization of ferritin and transferrin saturation) 1
- If response is inadequate:
- Consider increasing the daily dose or switching to twice-daily dosing
- Try an alternate oral iron preparation if not tolerated
- Consider intravenous iron if oral iron is not effective, not absorbed, or not tolerated 1
Duration of Treatment
Continue iron replacement for approximately 3 months after normalization of hemoglobin levels to ensure adequate repletion of iron stores 1, 5
Common Pitfalls to Avoid
- Overdosing: Higher doses (>100 mg elemental iron daily) do not improve absorption and may increase side effects
- Inadequate duration: Stopping treatment once hemoglobin normalizes without replenishing iron stores
- Ignoring side effects: Gastrointestinal side effects are common and may reduce compliance
- Failure to identify cause: Not addressing the underlying cause of iron deficiency
- Inappropriate monitoring: Not checking response after 4 weeks of treatment
Special Considerations
For patients with poor tolerance to oral iron, consider: