De Pergola G, Ciampolillo A, Paolotti S, Trerotoli P, Giorgino R
Internal Medicine, Endocrinology, and Metabolic Diseases, Department of Emergency and Organ Transplantation, School of Medicine, University of Bari, Via Putignani 236, 70122 Bari, Italy.
Clin Endocrinol (Oxf). 2007 Aug;67(2):265-9. doi: 10.1111/j.1365-2265.2007.02874.x. Epub 2007 Jun 4.
To examine whether obesity, body fat distribution and insulin resistance have an independent effect on serum TSH and free thyroid hormones (FT3 and FT4) in a cohort of euthyroid women, represented by overweight and obese patients.
A total of 201 women, aged 18-68 years, with body mass index (BMI) > or = 25.0 kg/m(2) and TSH levels < 4.0 mU/l were investigated.
Fasting TSH, FT3, FT4, insulin, glucose, and serum lipid concentrations, and the level of insulin resistance, estimated by the homeostasis model assessment for insulin resistance (HOMA-IR). Waist circumference was measured as an indirect parameter of central fat accumulation.
FT3 was directly associated with BMI (P < 0.01) and waist circumference (P < 0.01), and negatively correlated with age (P < 0.001). FT4 was negatively associated with HOMA-IR (P < 0.05) and fasting insulin levels (P < 0.05). TSH was positively correlated with waist circumference (P < 0.05) and negatively associated with age (P < 0.05). When multiple regression analysis was performed with FT3 as the dependent variable, and waist circumference, HOMA-IR, blood pressure levels and serum lipid concentrations as independent variables, FT3 maintained an independent association only with waist circumference (positive, P < 0.05) and age (negative, P < 0.001). When multiple regression analysis was performed with TSH as the dependent variable, and the above parameters as independent variables, TSH maintained an independent association only with waist circumference (positive, P < 0.05) and age (negative, P < 0.05). By contrast, when multiple regression analysis was performed with FT4 as the dependent variable, FT4 did not maintain an independent association with any of the independent parameters.
Progressive central fat accumulation is associated with an increase in both FT3 and TSH serum levels, independently of insulin sensitivity, metabolic parameters and blood pressure. These results suggest that (1) progressive central fat accumulation is associated with a parallel increase in FT3 levels, possibly as an adaptive thermogenic phenomenon, and (2) the control of TSH secretion by free thyroid hormones is possibly impaired in obesity.
以超重和肥胖患者为代表，研究甲状腺功能正常的女性队列中肥胖、体脂分布和胰岛素抵抗是否对血清促甲状腺激素（TSH）和游离甲状腺激素（FT3和FT4）有独立影响。
共调查了201名年龄在18至68岁之间、体重指数（BMI）≥25.0kg/m²且TSH水平<4.0mU/l的女性。
空腹TSH、FT3、FT4、胰岛素、葡萄糖及血脂浓度，以及通过胰岛素抵抗稳态模型评估（HOMA-IR）估算的胰岛素抵抗水平。测量腰围作为中心性脂肪堆积的间接参数。
FT3与BMI（P<0.01）和腰围（P<0.01）直接相关，与年龄呈负相关（P<0.001）。FT4与HOMA-IR（P<0.05）和空腹胰岛素水平（P<0.05）呈负相关。TSH与腰围呈正相关（P<0.05），与年龄呈负相关（P<0.05）。以FT3为因变量，腰围、HOMA-IR、血压水平和血脂浓度为自变量进行多元回归分析时，FT3仅与腰围（正相关，P<0.05）和年龄（负相关，P<0.001）保持独立关联。以TSH为因变量，上述参数为自变量进行多元回归分析时，TSH仅与腰围（正相关，P<0.05）和年龄（负相关，P<0.05）保持独立关联。相比之下，以FT4为因变量进行多元回归分析时，FT4与任何自变量均无独立关联。
中心性脂肪堆积的进展与FT3和TSH血清水平升高相关，且独立于胰岛素敏感性、代谢参数和血压。这些结果表明：（1）中心性脂肪堆积的进展与FT3水平的平行升高相关，可能是一种适应性产热现象；（2）肥胖时游离甲状腺激素对TSH分泌的控制可能受损。
