Effects of altitude on thyroid disorders according to Chinese three-rung, ladder-like topography: national cross-sectional study oleh Boshen Gong, Youmin Wang, Jin-an Zhang, Qiao Zhang, Jiajun Zhao, Jiashu Li, Xichang Wang, Yutong Han, Ziwei Yu, Chenyu Zhang, Bingcong Peng, Yumin Xing, Qiuxian Li, Ping Wang, Yongze Li, Weiping Teng, Zhongyan Shan