What is the treatment for low ferritin (iron) levels with iron infusion?

Treatment of Low Ferritin Levels with Iron Infusion

Intravenous iron should be used if the patient does not tolerate oral iron, ferritin levels do not improve with a trial of oral iron, or the patient has a condition in which oral iron is not likely to be absorbed. 1

Initial Assessment and Diagnosis

• Low ferritin levels indicate iron deficiency, which should be treated when associated with anemia and/or low ferritin levels 1
• A full investigation of iron status should be performed in cases of anemia and persistent major fatigue 1
• Baseline blood tests should include hemoglobin concentration, hematocrit, mean cellular volume, mean cellular hemoglobin, percentage of hypochromic erythrocytes, and serum ferritin levels 2
• For healthy adults >15 years, a ferritin cut-off of 30 µg/L is appropriate for diagnosing iron deficiency 2
• For children 6-12 years and adolescents 12-15 years, cut-offs of 15 and 20 µg/L, respectively, are recommended 2

Treatment Algorithm

First-Line Treatment: Oral Iron

• Oral iron supplementation is the first-line treatment for iron deficiency 1, 2
• Typical doses of oral iron supplements are 100-200 mg/day, in divided doses 1
• Ferrous sulfate is preferred as the least expensive iron formulation 1
• Consider once-daily or alternate-day dosing to improve absorption and reduce side effects 1
• Adding vitamin C to oral iron supplementation improves absorption 1

When to Consider IV Iron Therapy

IV iron administration is indicated in the following situations:

• Patients not reaching target therapeutic goals with oral supplementation 1
• Those requiring rapid iron repletion (e.g., before elective surgery) 1
• Repeated failure of oral therapy 1
• Patients who cannot tolerate oral iron due to gastrointestinal side effects 1, 3
• Conditions with impaired iron absorption (e.g., inflammatory bowel disease, bariatric surgery) 1, 4
• Patients with active inflammation and compromised absorption 1

IV Iron Administration

Formulation Selection

• Modern IV iron formulations include iron sucrose, ferric carboxymaltose, iron derisomaltose, ferrumoxytol, and iron gluconate 5
• Intravenous iron formulations that can replace iron deficits with 1 or 2 infusions are preferred over those requiring multiple infusions 1
• Ferric carboxymaltose allows for controlled delivery of iron to target tissues and can deliver up to 1000 mg during ≤15 minutes administration time 6

Dosing Recommendations

• For significant iron deficiency, a single IV dose of whole-body iron replacement should be given, as 1 g of iron provided as a large single dose over 15 minutes using one of the recent carbohydrate products 1
• Iron sucrose can be administered in doses of 100 mg during sequential sessions until the pre-determined total dose is administered 7
• The dose should be adjusted for each patient to maintain the lowest hemoglobin level sufficient to avoid red blood cell transfusion 1

Safety Considerations

• Reactions during iron infusions are very infrequent (<1:250,000 administrations with recent formulations) but may be life-threatening 1
• All IV iron preparations are associated with a risk of infusion reactions, affecting <1% of patients 5
• Iron supplementation in the presence of normal or high ferritin values is not recommended and potentially harmful 1, 2
• Monitor for hypophosphatemia, which can affect 50-74% of patients treated with ferric carboxymaltose 5

Monitoring Treatment Response

• To measure the success of treatment, basic blood tests should be repeated after 8-10 weeks 1, 2
• Do not check iron studies earlier than 8-10 weeks after iron infusion as ferritin levels are falsely high immediately after infusion 1
• Patients with repeatedly low ferritin will benefit from intermittent oral substitution and long-term follow-up with basic blood tests repeated every 6 or 12 months 2

Special Populations

• In patients with chronic kidney disease, IV iron may be considered despite elevated ferritin if transferrin saturation is low 4
• For patients with inflammatory bowel disease and iron-deficiency anemia with active inflammation, IV iron therapy is recommended due to compromised absorption 1
• After bariatric procedures, particularly those disrupting normal duodenal iron absorption, IV iron therapy should be used 1

Common Pitfalls and Caveats

• Iron overload can occur with excessive supplementation, leading to chronic fatigue, joint pain, diabetes, and end-organ failure 1
• Withhold iron therapy when ferritin exceeds 1000 ng/mL or transferrin saturation exceeds 50% in dialysis patients 4
• In the presence of inflammation, serum ferritin can be falsely normal despite iron deficiency; transferrin saturation is a more reliable indicator 4, 5
• There is no role for intramuscular injections of iron 8