Cattedra di Medicina Interna, Dipartimento di Medicina, Chirurgia e Odontoiatria, Università degli Studi di Milano, Milan, Italy.
Obesity (Silver Spring). 2010 Apr;18(4):854-7. doi: 10.1038/oby.2009.320. Epub 2009 Oct 15.
Studies on thyroid function in obesity yielded inconsistent results; high thyroid-stimulating hormone (TSH) levels were generally shown; high free triiodothyronine (fT)-3 or fT4 levels were described in some, but not in other studies. After weight loss, TSH and thyroid hormones have been described to either increase or decrease. Our aim was to describe TSH, fT3, and fT4 in obese subjects with normal thyroid function before and after durable and significant weight loss, obtained through laparoscopic gastric banding (LAGB), in comparison with nonobese subjects. TSH, fT3, fT4, and fT3/fT4 ratio (an index of D1 and D2 deiodinase activity), were evaluated in 99 healthy controls and in 258 obese subjects, at baseline and 6 months, 1 year, and 2 years after LAGB, together with indexes of glucose (glucose, insulin, homeostasis model assessment of insulin resistance index) and lipid (triglycerides, total and high-density lipoprotein-cholesterol) metabolism, and anthropometric measures (BMI and waist circumference). Under basal conditions, TSH, fT3, and fT4 were all in the normal range, but higher in obese than in nonobese subjects, and fT3/fT4 ratio was normal; with weight loss, fT3 and fT3/fT4 ratio decreased in obese subjects, while fT4 increased and TSH remained steady; all values were again within the normal range. Albumin and cholesterol levels remained steady, while triglycerides, insulin, and homeostasis model assessment of insulin resistance decreased, and high-density lipoprotein-cholesterol increased. These changes, however, do not modify TSH, letting us to hypothesize that the changes are due to a decrease of D1 and D2 deiodinase activities.
关于甲状腺功能与肥胖之间的研究结果并不一致；通常情况下，促甲状腺激素（TSH）水平升高；而一些研究显示游离三碘甲状腺原氨酸（fT3）或游离甲状腺素（fT4）水平升高，另一些研究则没有显示。体重减轻后，TSH 和甲状腺激素的水平要么升高，要么降低。我们的目的是描述在通过腹腔镜胃带术（LAGB）获得持久且显著减肥的肥胖患者中，甲状腺功能正常的患者在减肥前后的 TSH、fT3 和 fT4 的变化情况，并与非肥胖患者进行比较。我们评估了 99 名健康对照者和 258 名肥胖患者在基线和 LAGB 后 6 个月、1 年和 2 年时的 TSH、fT3、fT4 和 fT3/fT4 比值（D1 和 D2 脱碘酶活性的一个指标），以及葡萄糖（血糖、胰岛素、胰岛素抵抗指数评估的稳态模型）和脂质（甘油三酯、总胆固醇和高密度脂蛋白胆固醇）代谢指标，以及人体测量学指标（BMI 和腰围）。在基础状态下，TSH、fT3 和 fT4 均处于正常范围内，但肥胖者高于非肥胖者，fT3/fT4 比值正常；随着体重减轻，肥胖者的 fT3 和 fT3/fT4 比值降低，而 fT4 增加，TSH 保持稳定；所有值再次处于正常范围内。白蛋白和胆固醇水平保持稳定，而甘油三酯、胰岛素和胰岛素抵抗指数评估的稳态模型降低，高密度脂蛋白胆固醇增加。然而，这些变化并没有改变 TSH，这让我们假设这些变化是由于 D1 和 D2 脱碘酶活性降低所致。
