Treatment of Low Ferritin (Iron Deficiency)
All patients with low ferritin should receive oral iron supplementation to correct deficiency and replenish body stores, with ferrous sulfate 200 mg three times daily as the first-line, most cost-effective option. 1
First-Line Oral Iron Therapy
- Start ferrous sulfate 200 mg three times daily as the simplest and cheapest option 1
- Ferrous gluconate and ferrous fumarate are equally effective alternatives 1
- Typical dosing range is 100-200 mg elemental iron per day in divided doses 1
- Recent evidence suggests alternate-day dosing may improve absorption and reduce side effects 1
- Liquid preparations may be tolerated when tablets are not 1
Enhancing Absorption
- Add ascorbic acid (vitamin C) 250-500 mg twice daily with iron to enhance absorption, particularly when response is poor 1
- Integrate heme and free iron regularly into the diet while avoiding inhibitors of iron uptake 1
Treatment Duration and Monitoring
- Continue iron supplementation for three months after correction of anemia to replenish iron stores 1
- Hemoglobin should rise by 2 g/dL after 3-4 weeks of treatment 1
- Repeat blood tests (hemoglobin, ferritin, MCV) after 8-10 weeks to assess treatment success 1, 2
- Do not check ferritin earlier after IV iron as levels are falsely elevated 1
Long-Term Follow-Up
- Monitor hemoglobin and red cell indices every 3 months for 1 year, then after another year 1
- Give additional oral iron if hemoglobin or MCV falls below normal 1
- Patients with repeatedly low ferritin benefit from intermittent oral supplementation every 6-12 months 2
Intravenous Iron Indications
Switch to IV iron when:
- Intolerance to at least two oral preparations 1
- Poor absorption (celiac disease, post-bariatric surgery, inflammatory bowel disease) 1, 3
- Chronic inflammatory conditions (CKD, heart failure, IBD, cancer) 1, 3
- Ongoing blood loss requiring rapid replacement 1, 3
- Second and third trimesters of pregnancy 1, 3
- Failure to respond to oral therapy despite adequate compliance 1
IV Iron Formulations
- Ferric carboxymaltose (Ferinject): 1000 mg over 15 minutes is the best-studied option with lowest risk profile 1
- Iron sucrose (Venofer): 200 mg over 10 minutes, may require multiple administrations 1
- Iron dextran (Cosmofer): 20 mg/kg over 6 hours, highest risk of anaphylaxis (0.6-0.7%) 1
- Resuscitation facilities must be available for all IV iron administration 1
Common Pitfalls and Caveats
Failure to Respond to Oral Iron
If hemoglobin fails to rise by 2 g/dL after 3-4 weeks, consider: 1
- Poor compliance (most common cause)
- Misdiagnosis
- Continued blood loss
- Malabsorption
- Concurrent inflammation masking ferritin levels 1
Inflammation Considerations
- Ferritin is an acute-phase reactant and can be falsely elevated in inflammation, infection, or chronic disease 1
- Check C-reactive protein to exclude acute phase reaction when ferritin interpretation is uncertain 2
- In inflammatory conditions, transferrin saturation <20% or hepcidin levels are more reliable indicators of true iron deficiency 1
Important Contraindications
- Never supplement iron when ferritin is normal or high—this is potentially harmful 1, 2
- Avoid iron-containing vitamin preparations and iron-supplemented foods during treatment 1
- Long-term daily supplementation with normal ferritin values is not recommended 2
Special Populations
Premenopausal Women
- Iron deficiency occurs in 5-10% of menstruating women 1
- Menstrual loss, pregnancy, and breastfeeding are usually responsible 1
- Women >45 years require full gastrointestinal investigation per standard guidelines 1