Iron Sucrose and Infection Risk
Iron sucrose, like all intravenous iron preparations, is associated with a modest but statistically significant increased risk of infection (16 additional infections per 1,000 patients treated), and this risk must be weighed against the benefits of treating anemia, particularly avoiding use in patients with active infections. 1
Magnitude of Infection Risk
A comprehensive meta-analysis of 154 randomized controlled trials involving 32,762 participants found that intravenous iron (including iron sucrose as the most commonly studied preparation with 68 trials) increased infection risk with a relative risk of 1.16 (95% CI: 1.03-1.29, moderate-quality evidence). 1
In absolute terms, this translates to 16 additional people per 1,000 developing an infection when receiving intravenous iron compared to oral iron or no iron (95% CI: 3-29 additional infections). 1
The infection risk was particularly elevated in patients with inflammatory bowel disease (RR 1.73; 95% CI: 1.11-2.71), where up to 90% of patients may have iron deficiency. 1
When only low-risk-of-bias studies were analyzed, the relative risk was 1.13 (95% CI: 0.97-1.32), suggesting the effect persists but with wider confidence intervals. 1
Mechanism of Increased Infection Risk
Intravenous iron increases circulating non-transferrin-bound iron, which provides essential nutrients for pathogen replication and growth. 2
This disrupts "nutritional immunity"—the body's natural defense mechanism of sequestering free iron during infections to limit bacterial proliferation. 2
Common nosocomial pathogens such as Staphylococcus aureus and Staphylococcus epidermidis have evolved iron acquisition mechanisms and can convert from benign colonization to virulent infection when exogenous iron becomes available. 1, 2
The lung was identified as the most common anatomical site of infection in studies that reported this detail. 1
Clinical Decision-Making Algorithm
Contraindications - Do Not Administer:
Defer iron sucrose administration in any patient with active soft tissue infection or other active infections until completely resolved and treated. 2, 3
The National Comprehensive Cancer Network recommends against iron supplementation in patients with active infection. 3
High-Risk Scenarios Requiring Careful Consideration:
Patients with inflammatory bowel disease face the highest infection risk and require particularly careful risk-benefit assessment. 1
Clinical settings with high endemic infection burdens warrant extra caution, as iron supplementation may be neither effective nor safe in these contexts. 1
Immunosuppressed patients (including those on biologics for IBD) face compounded infection risks. 1
When Benefits May Outweigh Risks:
Iron sucrose remains appropriate for patients without active infection who have failed oral iron therapy, have malabsorption, or require rapid iron repletion. 4, 5, 6
In chronic kidney disease, inflammatory bowel disease, and chronic heart failure, intravenous iron has become first-line treatment despite infection concerns. 4, 6
Iron sucrose demonstrates superior efficacy with 84-94% of patients achieving hemoglobin increases ≥2 g/dL, compared to only 21% continuing oral iron. 3, 5
Important Caveats and Pitfalls
No specific iron preparation (including iron sucrose) demonstrated superiority over others regarding infection risk, despite theoretical advantages of newer formulations with lower free iron concentrations. 1
Both single-dose and multiple-dose administrations were associated with increased infection risk, so dosing strategy does not mitigate this concern. 1
Baseline iron parameters (ferritin, transferrin saturation, hemoglobin) did not predict infection risk in meta-regression analysis, though data were limited. 1
For patients with ferritin >700 ng/mL, data on safety are conflicting and extra caution is warranted. 1
Practical Management Recommendations
If anemia requires urgent treatment during active infection, consider red blood cell transfusion rather than iron sucrose. 2
Intravenous iron reduces transfusion requirements overall (RR 0.93; 95% CI: 0.76-0.89), which may offset infection risks in appropriate patients. 1
Iron sucrose is generally well-tolerated with acceptable safety profiles when using appropriate dosing (typically 200 mg per infusion) and monitoring, with anaphylaxis being rare. 5, 6, 7
Monitor patients during and for at least 30 minutes after administration until clinically stable. 3
The benefits of correcting anemia (improved hemoglobin by 3-4 g/dL, reduced transfusions, improved quality of life) must be explicitly balanced against the 1.6% absolute increase in infection risk. 1, 5