What is the recommended treatment for a patient with low ferritin (iron) levels?

Treatment of Low Ferritin (Iron Deficiency)

Oral iron supplementation with ferrous sulfate 200 mg three times daily is the first-line treatment for low ferritin, though once-daily or alternate-day dosing may improve tolerability with similar efficacy; intravenous iron should be reserved for patients who cannot tolerate oral iron, fail to respond, or have conditions preventing oral absorption. 1

First-Line Treatment: Oral Iron Supplementation

Preferred Formulation and Dosing

• Ferrous sulfate is the preferred oral iron formulation as it is the least expensive and most effective option, with no single formulation demonstrating superiority over others 1, 2

• Standard dosing is ferrous sulfate 200 mg three times daily (providing approximately 65 mg elemental iron per dose), though this can be adjusted based on tolerability 1

• Once-daily or alternate-day dosing may be equally effective and better tolerated than traditional three-times-daily regimens, with similar rates of iron absorption and fewer gastrointestinal side effects 1, 3, 4

• Duration of treatment should be 3 months after correction of anemia to adequately replenish iron stores 1

Enhancing Absorption

• Add vitamin C (ascorbic acid) to oral iron supplementation to enhance iron absorption, particularly when response is poor 1

• Typical doses of oral iron supplements range from 100-200 mg/day of elemental iron 1

Monitoring Response to Oral Iron

• Hemoglobin should rise by 2 g/dL after 3-4 weeks of treatment 1

• Failure to achieve this response indicates poor compliance, misdiagnosis, continued blood loss, or malabsorption 1

• Monitor hemoglobin and red cell indices at 3-month intervals for one year, then annually after normalization 1

• Ferritin levels should be measured after 8-10 weeks of treatment, not earlier, as levels may be falsely elevated immediately after iron supplementation 1

Indications for Intravenous Iron

Intravenous iron is indicated when: 1

• The patient does not tolerate oral iron (gastrointestinal side effects are common, including constipation, diarrhea, and nausea)
• Ferritin levels do not improve after an adequate trial of oral iron
• The patient has a condition preventing oral iron absorption (inflammatory bowel disease with active inflammation, post-bariatric surgery, celiac disease)
• Rapid iron repletion is required (e.g., pre-operative patient blood management)

IV Iron Formulations and Administration

• Prefer IV iron formulations that can replace iron deficits with 1-2 infusions (such as ferric carboxymaltose or ferric derisomaltose at 500-1000 mg per infusion) over those requiring multiple administrations 1, 3

• All IV iron formulations have similar safety profiles; true anaphylaxis is very rare (<1:250,000 administrations), with most reactions being complement activation-related pseudo-allergy (infusion reactions) 1

• IV iron should always be administered in medical facilities by healthcare providers trained to manage hypersensitivity reactions 3

• Monitor phosphate levels after IV iron administration, particularly with ferric carboxymaltose, which has been associated with hypophosphatemia 3

Special Populations

Inflammatory Bowel Disease

• Determine whether iron deficiency is due to inadequate intake/absorption or blood loss 1

• Use IV iron in patients with active inflammation that compromises absorption 1

• Treat active inflammation effectively to enhance iron absorption or reduce iron depletion 1

Post-Bariatric Surgery

• IV iron therapy should be used in patients who have undergone bariatric procedures that disrupt normal duodenal iron absorption, particularly when there is no identifiable source of chronic gastrointestinal blood loss 1

Chronic Kidney Disease

• Target transferrin saturation ≥20% and serum ferritin ≥100 ng/mL in dialysis patients 1

• Most hemodialysis patients require IV iron to maintain adequate iron stores during erythropoietin therapy 1

• Monitor serum ferritin and avoid chronic elevation above 500 ng/mL to prevent potential iron toxicity 1

Critical Monitoring Parameters

• Serum ferritin should preferably not exceed 500 mg/L to avoid toxicity of iron overload, especially in children and adolescents 1

• In patients receiving IV iron for genetic disorders of iron metabolism, doses should be calculated based on hemoglobin deficit and iron store requirements, repeated every 3-7 days until total dose is administered 1

• Iron supplementation should be avoided when ferritin is normal or elevated, as this is potentially harmful 1

Common Pitfalls to Avoid

• Do not perform fecal occult blood testing for iron deficiency evaluation—it is insensitive and non-specific 1

• Do not use parenteral iron as first-line therapy unless oral iron is contraindicated; it is more expensive, painful (when given intramuscularly), and carries risk of anaphylactic reactions 1

• Do not check ferritin levels too early after IV iron administration, as they will be falsely elevated 1

• Do not continue oral iron indefinitely without monitoring; once hemoglobin normalizes, continue for 3 months to replenish stores, then monitor periodically 1