3. Collection of healthy control group： According to the characteristic of CKD patient group, we will select the health control group carefully (paired selection of CKD patient group, 1:1). The rules of paired selection : 1. Sex 2.Age ± 5 years 3.Location -- CKD patient and health people are get from the same hospital. Health people who had no any chronic disease and required a physical checkup which get from the hospital (This hospital should be qualified to the renal disease improving institute) will be chosen into this project. Fifteen hundred people will be taken in this plan.