Effect of iron supplementation on thyroid hormone levels and resting metabolic rate in two college female athletes: a case study.
Iron plays an important role in thyroid hormone metabolism; thus, iron deficiency anemia may lead to alterations in resting metabolic rate (RMR). Based on this premise, two iron-deficient-anemic female athletes, 18 (A1) and 21 (A2) years of age, were supplemented with 23 mg/day of elemental iron to assess its effects on iron and thyroid hormone status and RMR at 0, 8, and 16 weeks. Anemia was clinically corrected in both subjects (hemoglobin: A1 = 11.0 to 13.0 to 12.6 g/dL and A2 = 11.5 to 13.9 to 12.6 g/dL, 0 to 8 to 16 weeks, respectively). Serum ferritin (SF) concentration also improved in both subjects (A1: 5.0 to 11.0 to 15.0 ng/dL and A2: 5.0 to 16.0 to 20.0 ng/dL; 0 to 8 to 16 weeks, respectively); however, 16 weeks of iron supplementation did not fully replete iron stores. A2 increased dietary iron and ascorbic acid intakes from 8 to 16 weeks, possibly accounting for her higher SF concentrations. RMR and total thyroxine changed over time: A1 increased while A2 decreased in these variables. Although clinical correction of iron deficiency anemia occurred after 16 weeks of low-level iron supplementation, RMR and thyroid hormone metabolism were oppositely affected in the two subjects.
Harris Rosenzweig
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Department of Nutrition, University of Massachusetts, Amherst, MA 01003-1420, USA.
Volpe
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D000293:Adolescent; D000328:Adult; D018798:Anemia, Iron-Deficiency / Q000178:diet therapy*; D001481:Basal Metabolism / Q000187:drug effects*; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D007501:Iron / Q000097:blood; D000090463:Iron Deficiencies; D019266:Iron, Dietary / Q000008:administration & dosage* / Q000494:pharmacology; D013961:Thyroid Gland / Q000187:drug effects* / Q000378:metabolism; D013963:Thyroid Hormones / Q000378:metabolism*; D013997:Time Factors
D019266:Iron, Dietary; D013963:Thyroid Hormones; D007501:Iron