Iron supplementation does not worsen respiratory health or alter the sputum microbiome in cystic fibrosis

Author Posting. © The Author(s), 2013. This is the author's version of the work. It is posted here by permission of Elsevier for personal use, not for redistribution. The definitive version was published in Journal of Cystic Fibrosis 13 (2014): 311-318, doi:10.1016/j.jcf.2013.11.004.Iron supplementation for hypoferremic anemia could potentiate bacterial growth in the cystic fibrosis (CF) lung, but clinical trials testing this hypothesis are lacking. Twenty-two adults with CF and hypoferremic anemia participated in a randomized, double-blind, placebo-controlled, crossover trial of ferrous sulfate 325 mg daily for 6 weeks. Iron-related hematologic parameters, anthropometric data, sputum iron, Akron Pulmonary Exacerbation Score (PES), and the sputum microbiome were serially assessed. Fixed-effect models were used to describe how ferrous sulfate affected these variables. Ferrous sulfate increased serum iron by 22.3% and transferrin saturation (TSAT) by 26.8% from baseline (p < 0.05) but did not affect hemoglobin, sputum iron, Akron PES, and the sputum microbiome. Low-dose ferrous sulfate improved hypoferremia without correcting anemia after 6 weeks. We did not observe significant effects on sputum iron, Akron PES, and the sputum microbiome. Although we did not identify untoward health effects of iron supplementation, a larger blinded randomized controlled trial would be needed to fully demonstrate safety.Flatley Foundation of Boston, Massachusetts; NIH P20-GM103413-10 and R01-HL074185-09; Cystic Fibrosis Foundation Research Development Program; Hitchcock Foundation; and NIH R01 AI0911699