Clinical Question: In hospitalized adults with iron-deficiency anemia (IDA) and concurrent acute infection, does IV iron administration improve clinical outcomes or worsen the infection?
Background: Iron-deficiency anemia affects up to 40% of hospitalized patients and is associated with worse outcomes in both pneumonia and sepsis. IV iron has advantages over oral therapy for iron repletion: it avoids gastrointestinal (GI) side effects and corrects hemoglobin more quickly, a meaningful advantage when rapid correction is needed, or GI absorption is unreliable. Yet many clinicians avoid IV iron during active infection on the theory that iron fuels bacterial growth, potentially worsening the infection. A 2021 meta-analysis raised concerns about infection risk with IV iron, but more recent studies haven’t confirmed that signal, and large real-world data across common inpatient infections have been sparse.
Study Design: Retrospective, propensity- matched cohort study
Setting: 111 U.S. healthcare organizations in the TriNetX Research Network; January 2000 to June 2025
Synopsis: This study used TriNetX, a federated database of 111 U.S. healthcare organizations, to identify 339,145 adults with concurrent iron-deficiency anemia (IDA) and acute infection, specifically methicillin-resistant Staphylococcus aureus (MRSA) bacteremia, pneumonia, urinary tract infection (UTI), colitis, or cellulitis, who had received antibiotics within two days of diagnosis. Patients were divided by whether they received IV iron within seven days of the combined diagnosis and matched 1:1 on demographics, comorbidities, and laboratory values within each infection cohort; matched cohorts ranged from 4,432 to 19,281 pairs per infection type. Fourteen- and 90-day survival was significantly higher with IV iron across all five cohorts (90-day HR, 0.66 for pneumonia, 0.60 for colitis). Hemoglobin improved more at 60 to 90 days in the IV iron group across all five infection types; transfusion days were also lower in four of five cohorts. Length of stay was slightly longer in the MRSA bacteremia and UTI groups. The study is limited by its observational design, IDA defined by diagnosis code rather than laboratory criteria, IV iron exposure without dose information, infusion adverse events not tracked, and possible residual confounding.
Bottom Line: IV iron given during active infection is associated with improved survival and hemoglobin recovery across five common inpatient infection types, supporting its use even when infection is being treated concurrently.
Citation: Sohail H, et al. A retrospective, real-world study of IV iron use to treat iron deficiency anemia during acute infection. Blood. 2026;147(21):2518-2529. doi: 10.1182/blood.2025031965.
Dr. Narayan
Dr. Narayan is an academic hospitalist in the division of hospital medicine at MedStar Washington Hospital Center in Washington, D.C.