促甲状腺素在骨代谢中的作用

Effect of thyrotropin on bone metabolism

流行病学调查发现，甲状腺功能亢进症患者中，低促甲状腺素（TSH）与骨转换率增加、骨密度下降、骨折风险增加相关；即便甲状腺激素水平正常、TSH 水平降低的亚临床甲状腺功能亢进症（甲亢）患者，亦出现骨量减少，骨折风险增加，提示 TSH 具有独立于甲状腺激素而调节骨代谢的作用。 TSH 通过与破骨细胞上的 TSH 受体结合，抑制肿瘤坏死因子α（TNF-α）表达，发挥骨保护作用。 TSH 对骨代谢调节作用的确立，进一步奠定了垂体-骨代谢轴的理论基础。在临床上，应对亚临床甲亢、尤其是老年亚临床甲亢患者的骨代谢情况进行筛查，以及早发现和干预骨量减少、骨质疏松，减少骨折风险。

[Summary] Epidemiologic evidence favors strong correlations between low thyrotropin（TSH） and high bone turnover, low bone mineral density （ BMD）, and high fracture risk in hyperthyroid patients. Even subclinical hyperthyroidism, in which TSH is low and thyroid hormones are normal, is associated with osteopenia and osteoporosis. These evidences indicate that action of TSH on bone metabolism is independent of thyroid hormones and thus support the theory of the pituitary-bone axis. TSH plays its osteoprotective effect by binding TSH receptor on osteoclasts and inhibiting TNF-α expression. Physicians should screen the BMD in patients with overt and subclinical hyperthyroidism, especially the elderly, and make early diagnosis and better management for the underlying osteopenia and osteoporosis.