This systematic review aimed to assess and compare the effect of blood transfusion and intravenous iron therapy on the hemoglobin levels based on clinical trials. To do this, a search was conducted 25th of September 2024 by using PubMed, Cochrane, and Embase databases to identify studies comparing intravenous iron with blood transfusion in patients with iron deficiency anemia (<12 g/dL for women and <13 g/dL for men). The outcome selected was change in hemoglobin levels. The quality of the trials was assessed using Cochrane Risk of Bias Tool and Newcastle-Ottawa Quality Assessment Scale. We included 5 studies (three randomized controlled trials, 1 observational study and 1 retrospective study) comprising a total of 154,539 patients. Patient populations were heterogenous, encompassing surgical patients, patients undergoing hip fracture and pregnant women. Due to heterogeneity among the included studies, hemoglobin levels were reported at varying follow-up intervals. At 3 weeks follow-up or later after initial treatment, 3 studies reported significantly higher hemoglobin levels (ranging from 0.7 g/dL to 1.4 g/dL higher) in the intravenous iron group compared to the blood transfusion group. The remaining 2 studies found similar hemoglobin levels. Less than 3 weeks after initial treatment, 2 studies reported significantly higher hemoglobin levels in the blood transfusion group compared to the intravenous iron group. Our findings indicate that blood transfusion is more effective in achieving a rapid increase in hemoglobin levels shortly after therapy initiation, although this effect diminishes relatively swiftly. In contrast, intravenous iron seems to exert a more gradual increase in, but also longer lasting effect on, hemoglobin levels. However, our findings are limited by the small number of trials as well as questionable methodological quality of the included studies, resulting in a high risk of bias. Further investigation is warranted.

Bedan M, Lottrup C. Intravenous Iron Therapy Versus Blood Transfusion for Iron Deficiency Anemia: A Systematic Review. Transfus Med Rev. 2025 Jun 4;39(3):150905. doi: 10.1016/j.tmrv.2025.150905. Epub ahead of print. PMID: 40577932.