FNDC5 and chronic kidney disease: Subjects within the quartile 4 group of serum irisin had significantly the lowest prevalence rate of CKD (22.9%, 22.2%, 28.7% and 18.7% for quartile 1–4 groups, respectively, p = 0.046); and they also showed the lowest prevalence rate of albuminuira, although the difference was not statistically significant (20.4%, 18.6%, 25.1% and 16.9% for quartile 1–4 groups, respectively, p = 0.093).