Hess Sonja Y, Zimmermann Michael B, Arnold Myrtha, Langhans Wolfgang, Hurrell Richard F
Laboratory for Human Nutrition, Institute of Food Science, Swiss Federal Institute of Technology, Zürich, Switzerland.
J Nutr. 2002 Jul;132(7):1951-5. doi: 10.1093/jn/132.7.1951.
Studies in animals and humans have shown that iron deficiency anemia (IDA) impairs thyroid metabolism. However, the mechanism is not yet clear. The objective of this study was to investigate whether iron (Fe) deficiency lowers thyroid peroxidase (TPO) activity. TPO is a heme-containing enzyme catalyzing the two initial steps in thyroid hormone synthesis. Male weanling Sprague-Dawley rats (n = 84) were randomly assigned to seven groups. Three groups (ID-3, ID-7, ID-11) were fed an Fe-deficient diet containing 3, 7 and 11 microg Fe/g, respectively. Because IDA reduces food intake, three control groups were pair-fed Fe-sufficient diets (35 microg Fe/g) to each of the ID groups and one control group consumed food ad libitum. After 4 wk, hemoglobin, triiodothyronine (T(3)) and thyroxine (T(4)) were lower in the Fe-deficient groups than in the ad libitum control group (P < 0.001). By multiple regression, food restriction had a significant, independent effect on T(4) (P < 0.0001), but not on T(3). TPO activity (by both guaiacol and iodine assays) was markedly reduced by food restriction (P < 0.05). IDA also independently reduced TPO activity (P < 0.05). Compared with the ad libitum controls, TPO activity per thyroid determined by the guaiacol assay in the ID-3, ID-7 and ID-11 groups was decreased by 56, 45 and 33%, respectively (P < 0.05). These data indicate that Fe deficiency sharply reduces TPO activity and suggest that decreased TPO activity contributes to the adverse effects of IDA on thyroid metabolism.
对动物和人类的研究表明，缺铁性贫血（IDA）会损害甲状腺代谢。然而，其机制尚不清楚。本研究的目的是调查铁（Fe）缺乏是否会降低甲状腺过氧化物酶（TPO）的活性。TPO是一种含血红素的酶，催化甲状腺激素合成的两个初始步骤。将雄性断乳的Sprague-Dawley大鼠（n = 84）随机分为七组。三组（ID-3、ID-7、ID-11）分别喂食含铁量为3、7和11微克/克的缺铁饮食。由于缺铁性贫血会减少食物摄入量，因此将三个对照组与每个缺铁组配对喂食铁充足的饮食（35微克铁/克），还有一个对照组随意进食。4周后，缺铁组的血红蛋白、三碘甲状腺原氨酸（T(3)）和甲状腺素（T(4)）低于随意进食的对照组（P < 0.001）。通过多元回归分析，食物限制对T(4)有显著的独立影响（P < 0.0001），但对T(3)没有影响。食物限制显著降低了TPO活性（通过愈创木酚和碘测定法）（P < 0.05）。缺铁性贫血也独立降低了TPO活性（P < 0.05）。与随意进食的对照组相比，ID-3、ID-7和ID-11组通过愈创木酚测定法测定的每个甲状腺的TPO活性分别降低了56%、45%和33%（P < 0.05）。这些数据表明，铁缺乏会急剧降低TPO活性，并表明TPO活性降低是缺铁性贫血对甲状腺代谢产生不良影响的原因之一。
