<p>We recruited 41 healthy individuals from Physical Examination Center of the Affiliated Hospital of Xuzhou Medical University, then we informed them of the experimental procedure, and after their informed consent, they were included in the control group.</p>

<p>We recruited non-dialysis CKD patients who accepted treatment in the Department of Nephrology of the Affiliated Hospital of Xuzhou Medical University, we exculuded the patients who were combined with other diseases that can affect systemic blood circulation and vascular function, including cardiovascular, cerebrovascular, respiratory, endocrine, rheumatic immune diseases, infection, shock, dehydration, urgent dialysis, and other emergencies, 68 non-dialysis CKD patients were included in the CKD group after informed consent, after relevant examinations, 5 patients were excluded, and ultimately 63 non-dialysis CKD patients were included in the CKD group.</p>