Intravenous Iron Does Not Augment the Haemoglobin Mass Response to Simulated Hypoxia

ABSTRACTPURPOSEIron is integral for erythropoietic adaptation to hypoxia, yet the importance of supplementary iron compared to existing stores is poorly understood. The aim of the present study was to compare the magnitude of the haemoglobin mass (Hbmass) response to altitude in athletes supplemented with intravenous (IV), oral or placebo iron supplementation.METHODSThirty-four, non-anaemic, endurance-trained athletes completed 3 weeks of simulated altitude (3000 m, 14h.d−1), receiving either 2-3 bolus iron injections (ferric carboxymaltose), daily oral iron supplementation (ferrous sulphate) or a placebo, commencing 2 weeks prior to and throughout altitude exposure. Hbmass and markers of iron regulation were assessed at baseline (day -14), immediately prior to (day 0), weekly during (days 8, 15), and immediately, 1, 3 and 6 weeks after the completion of altitude exposure (days 22, 28, 42 and 63).RESULTSHbmass significantly increased following altitude in IV (Mean%, [90% CI]: 3.7%, [2.8, 4.7]) and oral (3.2%, [2.2, 4.2]), and remained elevated at 7 days post-altitude in oral (2.9%, [1.5, 4.3]) and 21 days post in IV (3.0%, [1.5, 4.6]). Hbmass was not significantly higher than baseline at any time point in placebo.CONCLUSIONIron supplementation appears necessary for optimal erythropoietic adaptation to altitude exposure. Intravenous iron supplementation during three weeks of simulated LHTL altitude training offered no additional benefit in terms of the magnitude of the erythropoietic response for non-anaemic endurance athletes compared to oral supplementation. PURPOSE Iron is integral for erythropoietic adaptation to hypoxia, yet the importance of supplementary iron compared to existing stores is poorly understood. The aim of the present study was to compare the magnitude of the haemoglobin mass (Hbmass) response to altitude in athletes supplemented with intravenous (IV), oral or placebo iron supplementation. METHODS Thirty-four, non-anaemic, endurance-trained athletes completed 3 weeks of simulated altitude (3000 m, 14h.d−1), receiving either 2-3 bolus iron injections (ferric carboxymaltose), daily oral iron supplementation (ferrous sulphate) or a placebo, commencing 2 weeks prior to and throughout altitude exposure. Hbmass and markers of iron regulation were assessed at baseline (day -14), immediately prior to (day 0), weekly during (days 8, 15), and immediately, 1, 3 and 6 weeks after the completion of altitude exposure (days 22, 28, 42 and 63). RESULTS Hbmass significantly increased following altitude in IV (Mean%, [90% CI]: 3.7%, [2.8, 4.7]) and oral (3.2%, [2.2, 4.2]), and remained elevated at 7 days post-altitude in oral (2.9%, [1.5, 4.3]) and 21 days post in IV (3.0%, [1.5, 4.6]). Hbmass was not significantly higher than baseline at any time point in placebo. CONCLUSION Iron supplementation appears necessary for optimal erythropoietic adaptation to altitude exposure. Intravenous iron supplementation during three weeks of simulated LHTL altitude training offered no additional benefit in terms of the magnitude of the erythropoietic response for non-anaemic endurance athletes compared to oral supplementation. Address for correspondence: Laura A. Garvican-Lewis, Physiology, Australian Institute of Sport, Leverrier Crescent, Bruce, ACT, 2616, Australia. Email: laura.lewis@ausport.gov.au; Tel: +61 2 6214 1145, Fax: +61 6214 1904 The authors declare no conflicts of interest. Funding for this study was received from a Partnership for Clean Competition Research Grant (cleancompetition.org). The results of the present study do not constitute endorsement by ACSM. The results of the study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation. Accepted for Publication: 7 March 2018 © 2018 American College of Sports Medicine

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