Marmara University Medical School, Endocrinology and Metabolism, Istanbul, Turkey.
Metab Syndr Relat Disord. 2012 Apr;10(2):137-42. doi: 10.1089/met.2011.0098. Epub 2012 Jan 9.
Obesity and metabolic syndrome are major health problems worldwide, including Turkey. Recent studies have shown an association between thyroid function tests and metabolic syndrome parameters. In this study, we aimed to determine the frequency of metabolic syndrome in an obese Turkish population and the relationship between metabolic syndrome and thyroid functions.
We recruited 211 patients (187 females/24 males; mean age, 39.7±11.7 years) with body mass index (BMI) >30 kg/m(2) and no other hormonal pathology that could cause obesity. Anthropometric evaluation was followed by measurement of fasting blood glucose (FBG), insulin, total cholesterol, triglycerides, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), thyroid-stimulating hormone (TSH), total triiodothyronine (TT3), total thyroxine (TT4), free T3 (FT3), and free T4 (FT4). Metabolic syndrome was defined according to the 2005 revision of the National Cholesterol Education Program Adult Panel III (NCEP ATP III) criteria. Insulin resistance was calculated from homeostasis model assessment of insulin resistance (HOMA-IR) formula. The TSH cutoff value was set at 2.5 mU/L.
Metabolic syndrome was diagnosed in 122 patients (58%). Metabolic syndrome positive patients had significantly higher FBG, triglycerides, FT4, systolic (SBP) and diastolic blood pressure (DBP), and statistically lower HDL-C and FT3/FT4 ratio than metabolic syndrome negative patients. TSH decreased with age and was not related with any metabolic syndrome parameters. The FT3/FT4 ratio negatively correlated with FBG, triglycerides, SBP, and DBP (P=0.003, r=-38; P=0.02, r=-0.28; P=0.005, r=-0.35; and P=0.007, r=-0.34, respectively); TT3 positively correlated with HOMA-IR (P=0.006, r=0.40), FBG (P=0.009, r=0.38), and waist circumference (P=0.02, r=0.34).
Metabolic syndrome frequency was increased in our study population compared to the general population. Metabolic syndrome parameters (except HDL) correlated with TT3, FT4, and the FT3/FT4 ratio. FT4 levels were associated with obesity and metabolic syndrome independently of insulin resistance, whereas TT3 levels were associated with both insulin resistance and metabolic syndrome. This relationship can be explained by compensatory effects of TT3, and probably FT4, on energy expenditure and thermogenesis in obese people.
肥胖和代谢综合征是全世界的主要健康问题，包括土耳其。最近的研究表明甲状腺功能测试与代谢综合征参数之间存在关联。在这项研究中，我们旨在确定肥胖的土耳其人群中代谢综合征的发生率，以及代谢综合征与甲状腺功能之间的关系。
我们招募了 211 名患者（187 名女性/24 名男性；平均年龄 39.7±11.7 岁），体重指数（BMI）>30kg/m2，且无其他可能导致肥胖的激素病理学。进行人体测量评估后，测量空腹血糖（FBG）、胰岛素、总胆固醇、甘油三酯、高密度脂蛋白胆固醇（HDL-C）、低密度脂蛋白胆固醇（LDL-C）、促甲状腺激素（TSH）、总三碘甲状腺原氨酸（TT3）、总甲状腺素（TT4）、游离 T3（FT3）和游离 T4（FT4）。代谢综合征根据 2005 年美国国家胆固醇教育计划成人专家组 III（NCEP ATP III）标准修订版进行定义。胰岛素抵抗用稳态模型评估的胰岛素抵抗（HOMA-IR）公式计算。TSH 截断值设定为 2.5mU/L。
诊断出 122 名患者（58%）患有代谢综合征。代谢综合征阳性患者的 FBG、甘油三酯、FT4、收缩压（SBP）和舒张压（DBP）显著升高，而高密度脂蛋白胆固醇和 FT3/FT4 比值显著降低。TSH 随年龄而降低，与任何代谢综合征参数均无关。FT3/FT4 比值与 FBG、甘油三酯、SBP 和 DBP 呈负相关（P=0.003，r=-38；P=0.02，r=-0.28；P=0.005，r=-0.35；P=0.007，r=-0.34）；TT3 与 HOMA-IR（P=0.006，r=0.40）、FBG（P=0.009，r=0.38）和腰围（P=0.02，r=0.34）呈正相关。
与一般人群相比，我们的研究人群中代谢综合征的发生率增加。代谢综合征参数（除 HDL 外）与 TT3、FT4 和 FT3/FT4 比值相关。FT4 水平与肥胖和代谢综合征独立相关，而 TT3 水平与肥胖和代谢综合征均相关。这种关系可以用 TT3 对能量消耗和肥胖者产热的代偿作用来解释，可能还与 FT4 有关。
