What is the recommended treatment for low ferritin and iron deficiency?

Treatment of Low Ferritin and Iron Deficiency

Iron deficiency should be treated when associated with anemia and/or low ferritin levels, with oral iron as first-line therapy (100-200 mg elemental iron daily) for most patients, while intravenous iron is reserved for specific clinical scenarios including intolerance to oral iron, malabsorption conditions, active inflammation, hemoglobin <100 g/L, or ongoing blood loss. 1

Diagnostic Thresholds

• Ferritin <30 ng/mL indicates iron deficiency in individuals without inflammatory conditions 2
• Transferrin saturation <20% serves as an alternative diagnostic marker 2
• In inflammatory conditions (IBD, CKD, heart failure), iron deficiency may exist with ferritin between 30-100 ng/mL; use transferrin saturation or hepcidin for confirmation 1
• All ferritin measurements should exclude acute inflammation by checking C-reactive protein, as ferritin is falsely elevated during inflammation 1, 3

First-Line Treatment: Oral Iron

Oral iron supplementation is the initial treatment for most patients with iron deficiency 1, 2:

• Dosage: 100-200 mg elemental iron daily in divided doses 1
• Standard formulation: Ferrous sulfate 324 mg (65 mg elemental iron) daily 4
• Alternate-day dosing (every other day) shows better iron absorption and fewer gastrointestinal side effects than daily dosing 1
• Avoid exceeding 100 mg elemental iron per day in IBD patients to minimize mucosal harm 1

Oral Iron Indications

• Mild anemia with clinically inactive disease 1
• No previous intolerance to oral iron 1
• Hemoglobin >100 g/L 1
• Absence of malabsorption conditions 1

Enhancing Oral Iron Absorption

• Co-administer vitamin C (250-500 mg) with iron to enhance absorption 1
• Avoid tea, coffee, and calcium supplements around iron dosing times 1
• Integrate heme iron sources (red meat) into diet 1, 3

Intravenous Iron Therapy

IV iron should be considered as first-line treatment in the following scenarios 1:

Absolute Indications

• Active inflammatory bowel disease with compromised absorption 1
• Hemoglobin <100 g/L 1
• Previous intolerance to oral iron (nausea, constipation, diarrhea) 1
• Malabsorption conditions: celiac disease, post-bariatric surgery, atrophic gastritis 1, 2
• Ongoing blood loss not responding to oral iron 1
• Second and third trimesters of pregnancy 2
• Chronic inflammatory conditions: CKD, heart failure, cancer 1, 2
• Need for rapid iron repletion (e.g., preoperative patient blood management) 1

IV Iron Dosing by Body Weight and Hemoglobin 1

Hemoglobin Level	Body Weight <70 kg	Body Weight ≥70 kg
100-120 g/L (women) or 100-130 g/L (men)	1000 mg	1500 mg
70-100 g/L	1500 mg	2000 mg

IV Iron Formulations

• Ferric carboxymaltose: 1000 mg single dose over 15 minutes, best studied formulation 1
• Iron sucrose: 200 mg over 10 minutes, requires multiple administrations 1
• Low molecular weight iron dextran: allows large single doses but requires test dose due to anaphylaxis risk 1
• Avoid high molecular weight iron dextran (highest anaphylaxis risk) 1

Safety Considerations

• Anaphylactic reactions occur in <1:250,000 administrations with modern formulations 1
• Resuscitation facilities must be available during IV iron infusion 1
• Test dose of 25 mg required for iron dextran only 1

Monitoring Treatment Response

• Repeat blood tests at 8-10 weeks after initiating treatment, not earlier after IV iron as ferritin is falsely elevated 1, 3
• Measure hemoglobin, ferritin, and transferrin saturation 1
• Do not recheck ferritin immediately after IV iron due to falsely high levels 1

Maintenance and Prevention

After successful treatment, monitor for recurrence 1:

• Every 3 months for the first year, then every 6-12 months 1, 3
• Re-treat with IV iron when ferritin drops <100 ng/mL or hemoglobin falls below 12 g/dL (women) or 13 g/dL (men) 1
• Rapid recurrence of iron deficiency suggests ongoing blood loss or subclinical inflammation requiring further investigation 1

Critical Safety Warnings

• Never supplement iron when ferritin is normal or elevated (potentially harmful) 1, 3
• Upper safety limits: transferrin saturation should not chronically exceed 50% and ferritin should not exceed 800 ng/mL 1
• In critically ill patients with inflammation, hepcidin is more reliable than transferrin saturation for diagnosing iron deficiency 1
• One study showed 1 g ferric carboxymaltose in critically ill patients reduced hospital stay and 90-day mortality 1