Despite associated improvements in hemoglobin and response to ESA, there remain concerns regarding IV iron as a possible contributor to inflammation, oxidative stress, and infection. A discussion of the riskbenefit ratio of IV iron in CKD (Garneata L. J Ren Nutr. 2008;18:40-45) proposes mechanisms by which IV iron may promote infection as “releas(ing) catalytically active iron, which is potentially available for bacterial growth,” and as an inhibitor of phagocytosis.
Though studies cited were conflicting in this regard, phosphate binders and antacids and increased levels of hepcidin, a hormone produced in response to inflammation. Although vitamin C can enhance iron absorption, there is concern that intake greater than 200 mg/day may promote calcium oxalate deposits.
In addition to the importance of iron adequacy in achieving anemia management, iron supplementation may also confer nonhematologic benefits. A review of these potential health improvements (Agarwal R. Am J Nephrol. 2007;27:565–571) discusses the effect of iron supplementation on immune function, physical performance, thermoregulation, cognition, restless legs syndrome, and aluminum absorption.
The author notes that “clinical symptomatology, such as fatigability, cold intolerance, failure to concentrate, and poor effort intolerance, is often attributed to anemia or uremia” and “that iron deficiency, per se, can cause these symptoms is poorly recognized.” Cited in the article are studies supporting the nonheme role of iron and physiologic mechanisms, particularly regarding cognitive function, where “extensive literature supports an important role of iron for neurotransmitter synthesis, uptake, and degradation.”
Iron adequacy may also improve quality-of-life measures in CKD patients. Results of an earlier study by Agarwal et al (Am J Nephrol. 2006;26:445-454) point to improvements in Kidney Disease Quality of Life scores associated with increases in ferritin and transferrin saturation following IV iron supplementation, independent of hemoglobin level. Although much of the information regarding the nonhematologic role of iron remains to be confirmed in the CKD population, it may be that role which underscores the importance of iron adequacy.