1. Department of Nephrology, Yantaishan Hospital, Yantai, Shandong 264000, P.R. China
2. Department of Respiratory Medicine, Yantai Yuhuangding Hospital, Yantai, Shandong 264000, P.R. China
3. Department of Internal Medicine, Laiyang Tuberculosis Prevention Institution, Laiyang, Shandong 265299, P.R. China