De Lorenzo A, Andreoli A, Fusco A, Magnani A, D'Orazio N, Bertoli A
Human Nutrition Unit, University of Rome Tor Vergata, Italy.
Horm Metab Res. 2000 Sep;32(9):359-63. doi: 10.1055/s-2007-978653.
The present study was aimed to assess the effects of subclinical hypothyroidism on body composition (BC).
Thirty-one women (age: 37 +/- 9.9 years) with a wide range of body mass index (BMI) were studied. Subclinical hypothyroidism was defined by a basal TSH > or = 4 mU/L and/or TRH stimulated peak > or = 30 mU/L.
For each subject, weight, height, BMI, multifrequency bioelectrical impedance spectroscopy (BIS) and D2O and NaBr dilution tests were performed to assessed total body water (TBW) and extracellular water (ECW). Thyroid function (basal and TRH stimulated TSH, free T3, and free T4) were determined from fasting blood samples for all subjects. Total body dual energy X-ray absorptiometry (DXA) were used to measure fat mass (FM) and lean mass (Lean).
The results of BIS were compared with the TBW and ECW estimated by the dilution techniques on the same individuals. The correlation was R2 = 0.65 for impedance at 5 kHz and ECW by NaBr and R2 = 0.72 for impedance at 100 kHz and TBW by D2O. Intracellular water (ICW) was calculated as differences between TBW and ECW measured by dilution methods. Percent of ECW and ICW were related to BMI (ANOVA, p < 0.001). No difference in TBW, body water distribution and body composition related to thyroid function was demonstrated.
In our patients affected with subclinical hypothyroidism, with or without obesity, only obesity appeared related to TBW, ECW and ICW; the subclinical hypothyroidism, on the contrary, had no effect on compartments of body fluids. Bioimpedance is a valid tool to assess body fluid distribution in subclinical hypothyroidism.
本研究旨在评估亚临床甲状腺功能减退对身体成分（BC）的影响。
对31名体重指数（BMI）范围广泛的女性（年龄：37±9.9岁）进行了研究。亚临床甲状腺功能减退的定义为基础促甲状腺激素（TSH）≥4 mU/L和/或促甲状腺激素释放激素（TRH）刺激后的峰值≥30 mU/L。
对每位受试者进行体重、身高、BMI、多频生物电阻抗光谱法（BIS）以及重水（D2O）和溴化钠稀释试验，以评估总体水（TBW）和细胞外液（ECW）。对所有受试者的空腹血样进行甲状腺功能（基础及TRH刺激后的TSH、游离三碘甲状腺原氨酸（free T3）和游离甲状腺素（free T4））检测。采用全身双能X线吸收法（DXA）测量脂肪量（FM）和去脂体重（Lean）。
将同一受试者的BIS结果与通过稀释技术估算的TBW和ECW进行比较。5 kHz时的阻抗与溴化钠法测得的ECW的相关性为R2 = 0.65，100 kHz时的阻抗与重水法测得的TBW的相关性为R2 = 0.72。细胞内液（ICW）通过稀释法测得的TBW与ECW的差值计算得出。ECW和ICW的百分比与BMI相关（方差分析，p < 0.001）。未发现与甲状腺功能相关的TBW、身体水分分布和身体成分存在差异。
在我们的亚临床甲状腺功能减退患者中，无论有无肥胖，仅肥胖与TBW、ECW和ICW相关；相反，亚临床甲状腺功能减退对体液成分无影响。生物电阻抗是评估亚临床甲状腺功能减退患者体液分布的有效工具。
