IV iron lowers mortality risk in anaemics

A retrospective study spanning 25 years has shown that intravenous (IV) iron therapy in hospitalized patients with iron-deficiency anaemia and acute infections is associated with a lower risk of death.

Propensity-matched analyses of patients with various types of bacterial infection, including methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia, pneumonia, and urinary tract infections (UTIs), showed that IV iron was associated with a 44-52% reduction in short-term mortality and a 27-40% reduction in long-term mortality. [ASH 2025, abstract 5]

Dr Haris Sohail from Charleston Area Medical Center, West Virginia, who presented at ASH 2025, said the findings challenge the belief that IV iron worsens outcomes in acute infections by nourishing bacteria. “Many patients have been left untreated during critical times when their body needed IV iron most, and until now, no large-scale study supported or refuted these concerns,” he said during a press briefing. “Old beliefs may be preventing our patients from receiving life-saving treatment.”

Controversial in infection settings

Dr Jacquelyn Powers of Texas Children’s Haematology Center in Houston, Texas, US, who introduced the study during the plenary session, said iron plays key roles in countless cellular processes. However, the critical micronutrient is restricted during acute infections, presumably by the immune system to reduce its availability to pathogens.

“IV iron is controversial in the setting of infection,” she said, noting that physicians have been trained to avoid it. “Iron is required by the patient for optimal health, but it is also essential to bacteria and viruses during inflammatory states.”

Old belief challenged

Dr Robert Sackstein from Harvard Medical School in Boston, Massachusetts, US, said the increase in ferritin during infections is to bind up iron. “It’s part of the innate immune response to protect against pathogens. So, your data is giving us a new pause on that theory or perception,” he told Sohail.

When asked how that perception has persisted for decades, Sohail responded that it was likely based on theoretical laboratory work in which researchers “saw that hydrophilic bacteria have a higher risk of growing when we give iron.” However, he said that in the setting of infection, patients are receiving antibiotics.

Researchers analysed data from the TriNetX Research Network to identify adult hospitalized patients with iron-deficiency anaemia and acute infections from 2002 to 2024. They compared those who received IV iron therapy in the week of the index infection with those who did not, matched for age, sex, race or ethnicity, comorbidities, haemoglobin, ferritin, and procalcitonin.

The analysis included 16,866 patients diagnosed with MRSA bacteraemia (8,433 who received iron and 8,433 who did not), 38,562 with pneumonia, 37,226 with a UTI, 8,864 with colitis, and 16,808 with cellulitis.

Across groups, approximately 40 percent had chronic kidney disease. Heart failure was a comorbidity in up to 40 percent of patients and over 50 percent in the pneumonia group. Mean haemoglobin ranged from 9.1 to 9.4 at baseline.

At 14 days after the index infection, survival outcomes between the IV iron and non-IV iron groups were as follows: MRSA bacteraemia: 97.6 percent vs 95 percent (HR, 0.48), pneumonia: 95.7 percent vs 91.5 percent (HR, 0.50), UTI: 97.6 percent vs 95.7 percent (HR,0.56), colitis: 97.6 percent vs 95.5 percent (HR, 0.52), and cellulitis: 98.5 percent vs 97.4 percent (HR, 0.55).

At 90 days, survival outcomes were as follows: MRSA bacteraemia: 88.6 percent vs 83.8 percent (HR, 0.67), pneumonia: 84.7 percent vs 78.1 percent (HR, 0.66), UTI: 89.1 percent vs 85.6 percent (HR, 0.73), colitis: 89.7 percent vs 83.8 percent (HR, 0.60), and cellulitis (HR, 92.2 percent vs 89.2 percent (HR, 0.70).

Patients treated with IV iron had fewer red blood cell transfusions and greater improvement in haemoglobin at both 14 days and 60–90 days. Haemoglobin increases consistently exceeded 1.2 g/dL in patients treated with IV iron vs 0.7 to 1 g/dL in those without iron.

Lengths of hospital stay were similar across all groups, except in the MRSA bacteraemia and UTI cohorts, which were slightly longer for those treated with IV iron (+0.1 and +0.3 days, respectively).