正常范围内血清甲状腺激素的变化与代谢正常肥胖的关系

The relationship between changes of serum thyroid hormone in normal range and obesity related disorders

目的了解正常范围内不同血清甲状腺激素水平个体发生肥胖及高血糖、血脂异常、高血压和代谢综合征（MS）的比例，分析不同肥胖亚型血清甲状腺激素从平均值的偏移情况，探讨正常范围内血清甲状腺激素变化及其与相关代谢疾病的关系。方法收集2013年11月至2014年2月既往无甲状腺疾病史及家族史且甲状腺功能正常者240例，记录一般情况、相关临床及生化指标，分别按照血清游离甲状腺素（FT4）、血清游离三碘甲状腺原氨酸（FT3）、血清促甲状腺激素（TSH）水平从低到高进行四分位数分组，比较各组间发生肥胖及其相关代谢异常的风险。比较正常体质量正常代谢组、代谢正常肥胖（MHO）组、肥胖伴血脂异常组、肥胖伴血糖异常组、肥胖伴MS组间血清甲状腺激素的变化情况。结果（1）正常范围血清盯，四分位数从低到高的分组，A1组、A2组、A3组肥胖伴MS的发生率较A4组增高（P〈0．05）。（2）正常范围血清FT4四分位数从低到高的分组，B1组、B2组肥胖伴MS的发生率较B4组增高（P〈0．05）。（3）正常范围血清TSH四分位数从低到高的分组，与P4组比较，P1组肥胖伴MS发生率明显增高，而MHO发生率较低（P〈0．05）。（4）血清甲状腺激素水平均值偏移后，与MHO组相比，肥胖伴血糖异常组、肥胖伴MS组血清FT3，降低；且肥胖伴MS组血清TSH水平降低（P〈0．05）。结论当FT3、FT4和TSH处于正常范围高值时，肥胖患者的代谢状况趋向正常，容易保持MHO的正常代谢状态。FT3、FT4和TSH均处于正常低值时，肥胖者更容易发生代谢紊乱，MS的发生率明显增加。正常范围内血清TSH水平的增高可能有利于MHO保持代谢正常状态。

Objective To investigate the proportion of obesity, hyperglycemia, dyslipidemia, hy- pertension and metabolic syndrome （MS） in different quarters of levels of serum thyroid hormones in normal range, calculate the fluctuation of serum thyroid hormones from the midline in different subtypes of obesity, and explore the relationship between the changes of serum thyroid hormones in normal range and obesity related disorders. Methods A total of 240 euthyroid subjects was evaluated for routine health examination in our hospital from November 2013 to February 2014 without history and family history of thyroid diseases. The general case, the relevant clinical and biochemical indicators were recorded. Clinical biochemical features and the risk factors of obesity related metabolic abnormalities were compared between different quar- tiles of serum free triiodothyronine （ FT3 ） , free thyroxine （ FT4 ） , and thyroid-stimulating hormone （TSH） in normal range. The changes of serum thyroid hormones were compared among metabolically healthy obese （MHO）, obese with dyslipidemia, obese with abnormal blood glucose, MS and those with normal weight and metabolic healthy. Results （1）In four quartiles of serum FT3 levels from the lowest group A1 to the highest group A4, groups A1, A2 and A3 had higher percentage of MS compared to group A4 （ P 〈0. 05 ）. （2） In four quartiles of serum FT4 levels from the lowest group B1 to the highest group B4, groups B1 and B2 had higher percentage of MS compared to group 114 （ P 〈 0. 05）. （3） In four quartiles of serum TSH levels from the lowest group P1 to the highest group P4, group P1 had higher percentage of MS and lower percent- age of MHO compared to group P4. （4） After the fluctuation values of serum FT3 , FT4, and TSH were calculated, serum FT3 level was found to be decreased in MHO group, obese group with abnormal glucose, obese group with MS; FT4 levels decreased in MHO and obese group with MS; and TSH levels increased in MHO and decreased in obese group with MS compared with normal controls （ P 〈 0. 05 ）. Conclusions When serum FT3 , FT4, and TSH values were in the highest quartile of normal range, the metabolic status of obese individuals tends to be normal, which is called MHO. When FT3, FT4, and TSH values were in the lowest quartile, obese individuals were often accompanied by metabolic disorders and MS. Increased serum TSH levels within normal range can help MHO maintain healthy metabolic state.