What form of iron is best to supplement with for women who menstruate and experience significant blood loss, such as after intrauterine device (IUD) insertion?

Iron Supplementation for Menstruating Women with IUD-Related Blood Loss

For women experiencing blood loss from Mirena insertion and ongoing menstruation, ferrous sulfate 200 mg taken once daily is the recommended first-line iron supplement, as it is the most cost-effective and equally efficacious as other oral iron formulations. 1, 2

Optimal Iron Formulation and Dosing

Ferrous sulfate is the preferred iron supplement because it has proven efficacy, low cost, and wide availability compared to other formulations. 1, 2 The traditional recommendation was 200 mg three times daily, but more recent evidence suggests once-daily or alternate-day dosing may be equally effective with better tolerability. 2

Equivalent Alternative Formulations

If ferrous sulfate is not tolerated, these alternatives are equally effective: 1, 3

• Ferrous fumarate 210 mg daily
• Ferrous gluconate 300 mg daily
• Liquid iron preparations may be better tolerated when tablets cause gastrointestinal side effects 1, 3

Enhancing Iron Absorption

Take iron supplements with vitamin C (ascorbic acid) to significantly enhance absorption, particularly if your response to iron is poor. 1, 3, 2 Specifically, 250-500 mg of vitamin C twice daily alongside iron can improve absorption. 2 Taking iron with citrus fruits or drinks provides this benefit naturally. 1

Critical Timing Consideration

Separate iron and calcium supplements by 1-2 hours to avoid interference with iron absorption. 1 This is particularly important if you're taking calcium-containing multivitamins or supplements.

Duration of Treatment

Continue iron supplementation for three months after your hemoglobin normalizes to adequately replenish iron stores. 3, 2 Stopping prematurely leads to recurrence of iron deficiency because body stores remain depleted even when hemoglobin appears normal. 3

Monitoring Your Response

Your healthcare provider should check: 3, 2

• Hemoglobin and red blood cell indices every 3 months for the first year, then once more after another year
• Ferritin levels if there's doubt about whether your iron stores are replenished
• Expected hemoglobin rise of 2 g/dL after 3-4 weeks of treatment 1, 2

If your hemoglobin or mean corpuscular volume (MCV) falls below normal during monitoring, additional iron supplementation should be restarted. 3, 2

Context for IUD-Related Blood Loss

Your situation with Mirena-related bleeding is clinically significant because: 1, 4

• IUD use is a recognized risk factor for iron deficiency in menstruating women due to increased menstrual blood loss
• Copper IUDs typically increase menstrual blood loss by 54-59% 5, though the levonorgestrel-releasing Mirena usually decreases bleeding over time 1
• Women with heavy menstrual blood loss (≥80 mL/month) affect approximately 10% of women of childbearing age 1

When Oral Iron Fails

Intravenous iron should only be considered if: 1, 3, 2

• You cannot tolerate at least two different oral iron preparations
• Your ferritin levels don't improve despite adequate oral iron trial
• You have documented non-compliance with oral therapy

Parenteral iron is more expensive, carries risk of anaphylactic reactions, and provides no faster hemoglobin rise than oral preparations. 1

Common Pitfalls to Avoid

• Don't stop iron too early: Many women discontinue supplementation once they feel better, but stores remain depleted 3
• Don't take iron with calcium, tea, or coffee: These significantly impair absorption 1
• Don't assume IV iron is superior: Oral iron is equally effective when taken properly and is much safer 1, 2
• Don't ignore persistent symptoms: If bleeding continues heavily or you don't respond to iron within 3-4 weeks, further gynecological evaluation may be needed 1