Fierabracci Paola, Martinelli Silvia, Tamberi Anna, Piaggi Paolo, Basolo Alessio, Pelosini Caterina, Ricco Ilaria, Magno Silvia, Querci Giorgia, Ceccarini Giovanni, Scartabelli Giovanna, Salvetti Guido, Vitti Paolo, Santini Ferruccio
Obesity Center, Endocrinology Unit 1, University Hospital of Pisa , Pisa, Italy .
Thyroid. 2016 Apr;26(4):499-503. doi: 10.1089/thy.2015.0473. Epub 2016 Mar 16.
Obesity and hypothyroidism are both common disorders within the general population. Obese hypothyroid subjects require higher doses of levothyroxine (LT4) compared with normal weight individuals. Previous studies on the effects of bariatric surgery on LT4 dose requirements in hypothyroid subjects have provided conflicting results. The aim of this study was to evaluate the LT4 requirements in a group of obese subjects with acquired hypothyroidism, before and after weight loss achieved by bariatric surgery.
Ninety-three obese hypothyroid subjects (mean age = 48 ± 9 years; mean body mass index = 45.9 ± 5.6 kg/m(2)), were evaluated before and 28 ± 8 months after bariatric surgery. Changes in the LT4 dose, anthropometric measures, and hormone values were evaluated. In 20 patients, data of body composition, assessed by dual energy X-ray absorptiometry, were also analyzed.
On average, after weight loss, a significant reduction of the total dose of LT4 was documented (from 130.6 ± 48.5 to 116.2 ± 38.6 μg/day; p < 0.001). The LT4 dose had to be reduced in 47 patients, was unchanged in 34, and had to be increased in 12 patients affected by autoimmune thyroiditis. Reduction of the LT4 dose was proportional to reduction of the lean body mass.
The weight loss achieved with modern surgical bariatric procedures is associated with a reduction of LT4 requirements in most hypothyroid subjects, which appears to be related to a decrease of the lean body mass. Occasionally, a concurrent decline of residual thyroid function, as it occurs in autoimmune thyroiditis, can counteract this phenomenon and eventually produce an increase of LT4 needs. It is believed that during the weight loss phase that follows bariatric surgery, there is no need for preventive adjustments of the LT4 dose, but serum thyroid hormones and thyrotropin should be periodically monitored in order to detect possible variations of LT4 requirements and to allow proper corrections of the therapy.
肥胖和甲状腺功能减退在普通人群中都是常见病症。与体重正常的个体相比，肥胖的甲状腺功能减退患者需要更高剂量的左甲状腺素（LT4）。先前关于减肥手术对甲状腺功能减退患者LT4剂量需求影响的研究结果相互矛盾。本研究的目的是评估一组因减肥手术实现体重减轻前后的肥胖获得性甲状腺功能减退患者的LT4需求。
93名肥胖的甲状腺功能减退患者（平均年龄 = 48 ± 9岁；平均体重指数 = 45.9 ± 5.6 kg/m²）在减肥手术前及术后28 ± 8个月接受评估。评估LT4剂量、人体测量指标和激素值的变化。对20名患者还分析了通过双能X线吸收法评估的身体成分数据。
平均而言，体重减轻后，记录到LT4总剂量显著降低（从130.6 ± 48.5降至116.2 ± 38.6 μg/天；p < 0.001）。47名患者的LT4剂量必须降低，34名患者不变，12名患有自身免疫性甲状腺炎的患者LT4剂量必须增加。LT4剂量的降低与去脂体重的减少成比例。
现代减肥手术实现的体重减轻与大多数甲状腺功能减退患者LT4需求的降低相关，这似乎与去脂体重的减少有关。偶尔，如自身免疫性甲状腺炎中发生的残余甲状腺功能同时下降，可抵消这一现象并最终导致LT4需求增加。据信在减肥手术后的体重减轻阶段，无需预防性调整LT�剂量，但应定期监测血清甲状腺激素和促甲状腺激素，以便检测LT4需求的可能变化并进行适当的治疗调整。
