SAN DIEGO—Dosing intravenous (IV) iron at higher TSAT levels has only a modest effect on raising transferrin saturation (TSAT), ferritin, and hemoglobin in anemic hemodialysis patients, investigators reported at Kidney Week 2012.

Bruce M. Robinson, MD, MS, of the Arbor Research Collaborative for Health and the University of Michigan in Ann Arbor, and colleagues analyzed monthly data from 15,183 hemodialysis patients in the Dialysis Outcomes and Practice Patterns Study (DOPPS). For patients prescribed IV iron, the investigators estimated the effects of iron dose within strata of current TSAT levels on the following month’s TSAT, ferritin, and hemoglobin values. As expected, IV iron dose was correlated with increases in these values the following month, but the associations were notably weaker for current TSAT of 30% or higher. In adjusted models, each 100 mg of iron increased next month’s TSAT by 0.43% for patients with TSAT below 30% compared with 0.10% for those with TSAT of 30% or higher. The effects of IV iron on ferritin and hemoglobin also were modest at TSAT of 30% or higher. Each 100 mg of iron increased next month’s ferritin level by 17 ng/mL for patients with TSAT below 30% compared with 7 ng/mL  for patients with TSAT of 30% or higher. Hemoglobin levels increased by 0.17 and 0.004 g/dL, respectively.

Dr. Robinson’s group summarized findings by noting that, although TSAT targets of 30% to 50% are now common in the United States, IV iron dosing raises TSAT and hemoglobin only modestly when given to patients with TSAT equal to or above 30%. They concluded that ongoing iron dosing when TSAT is 30% or higher “provides little erythropoietic support and may deleteriously increase parenchymal iron deposition. Additional study is needed, and until then caution is warranted.”

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