However, the clinical significance of age on the serum and urinary Klotho levels among the overall patients with CKD should be interpreted carefully, since our results demonstrated that the eGFR, but not age, was one of the pivotal predictive variables for the amount of urinary excreted Klotho in various CKD patients, while only the serum calcitriol was identified as a predictor of the serum soluble Klotho levels. This evidence concerns the gene KL and chronic kidney disease.