What is the recommended treatment for iron supplementation in patients with iron deficiency anemia?

Iron Supplementation in Iron Deficiency Anemia

Oral iron supplementation should be first-line treatment for most patients with iron deficiency anemia, while intravenous iron should be used for patients with active inflammatory bowel disease, previous intolerance to oral iron, hemoglobin below 10 g/dL, or those requiring erythropoiesis-stimulating agents. 1

Diagnosis and Confirmation

Before initiating treatment, iron deficiency anemia should be confirmed by:

• Serum ferritin: <30 μg/L in patients without inflammation; up to 100 μg/L may still indicate iron deficiency in the presence of inflammation 1, 2
• Transferrin saturation: <20% 2
• Hemoglobin: <12 g/dL in women, <13 g/dL in men 2

Oral Iron Supplementation

First-line Treatment

• Ferrous sulfate 200 mg (containing approximately 65 mg elemental iron) once daily is recommended as first-line treatment 1, 2
• No single oral iron formulation has proven advantages over others, but ferrous sulfate is preferred as the least expensive option 1

Dosing Strategy

• Once-daily dosing is sufficient and may improve tolerability 1
• Every-other-day dosing may be better tolerated with similar or equal rates of iron absorption 1, 3
• Morning administration is preferable as the circadian increase in plasma hepcidin is augmented by a morning iron dose 3
• Add vitamin C to oral iron supplementation to improve absorption 1

Duration of Treatment

• Continue treatment for 3 months after hemoglobin normalization to replenish iron stores 2
• An increase in hemoglobin of at least 2 g/dL within 4 weeks of treatment is an acceptable response 1

Intravenous Iron Supplementation

Indications for IV Iron

Intravenous iron should be considered as first-line treatment in:

• Patients with clinically active inflammatory bowel disease 1
• Previous intolerance to oral iron 1
• Hemoglobin below 10 g/dL 1
• Patients who need erythropoiesis-stimulating agents 1
• Patients with impaired absorption (celiac disease, post-bariatric surgery) 1, 4
• Chronic inflammatory conditions (chronic kidney disease, heart failure) 4
• Ongoing blood loss 4

Administration

• IV iron formulations that can replace iron deficits with 1 or 2 infusions are preferred over those requiring more than 2 infusions 1
• All IV iron formulations have similar risks; true anaphylaxis is very rare 1

Monitoring and Follow-up

• Check hemoglobin after 4 weeks of treatment (expect a rise of approximately 2 g/dL) 2
• Monitor ferritin and transferrin saturation 2-3 months after treatment 2
• Target values: ferritin >100 μg/L and transferrin saturation >20% 2

Special Considerations

Inflammatory Bowel Disease

• In IBD patients with anemia, determine whether iron deficiency is due to inadequate intake/absorption or iron loss from gastrointestinal bleeding 1
• Treat active inflammation effectively to enhance iron absorption or reduce iron depletion 1
• IV iron therapy should be given in IBD patients with iron deficiency anemia and active inflammation with compromised absorption 1

Pregnancy

• Iron requirements increase during pregnancy, particularly in the second and third trimesters 4
• IV iron may be indicated during the second and third trimesters of pregnancy when oral iron is not effective 4

Elderly Patients

• May benefit from IV iron due to better absorption, more rapid repletion of iron stores, and fewer GI side effects 2

Common Pitfalls and Caveats

• Avoid taking iron with tea, coffee, calcium, or fiber as these can inhibit absorption 1, 2
• Don't split oral iron doses throughout the day as this can increase side effects without improving absorption 3
• Recognize that ferritin is an acute phase reactant; in inflammatory states, ferritin up to 100 μg/L may still indicate iron deficiency 1
• Don't continue ineffective oral iron therapy; switch to IV iron if no response is seen after 4 weeks 2
• Be aware that IV iron reactions are usually complement activation-related pseudo-allergy (infusion reactions) rather than true anaphylaxis 1

By following these evidence-based recommendations, iron deficiency anemia can be effectively treated while minimizing side effects and optimizing patient outcomes.