en Nephrology Nephrology Original Article Original Article <span style="font-size:14px;"><span style="font-family:Times New Roman;"><span style="line-height:14pt"><b><i><span style="color:blue">Background</span></i></b><i><span style="color:blue">:</span></i> Endothelial dysfunction has a significant role in the pathogenesis of cardiovascular events in patients with kidney dysfunction. The present study aimed to compare the level of endothelial dysfunction in patients with chronic kidney disease (CKD) and acute kidney injury (AKI) by brachial artery flow-mediated dilation (FMD) technique. Also, we sought to find whether this non-invasive technique may assist in accurately distinguishing the acute or chronic nature of kidney failure in patients presenting with uremia for the first time.</span><br> <span style="line-height:14pt"><b><i><span style="color:blue">Methods:</span></i></b> Demographic and medical characteristics, and laboratory and renal ultrasonography data of the patients with AKI and CKD were collected and compared with a control group. Brachial artery FMD was measured using a Toshiba aplio 300 device with a 7.5 MHz linear probe.<span style="font-size:10.0pt"></span></span><br> <span style="line-height:14pt"><b><i><span style="color:blue">Results:</span></i></b> In a total of 175 patients with a mean (SD) age of 55.96(15.54) years, FMD% was significantly lower in the CKD and AKI patients compared to the control group (Mean&plusmn;SD: 16.28%&plusmn;10.52%), 16.28 %&plusmn;4.35%, and 24.24&plusmn;5.71, respectively, p<0.001). Among the different causes of AKI, contrast-induced nephropathy (10.78%&plusmn;1.75%), volume depletion (14.87%&plusmn;1.22%), and post-renal AKI (15.96%&plusmn;1.54%) had the lowest levels of FMD. Also, a significant correlation between FMD and eGFR (r=0.26, <i>P</i><0.001), serum Hb (r=0.18, <i>P</i>=0.013), Na (r=0.19, <i>P</i>=0.011), BUN (r=-0.21,<i> P</i>=0.005) and Cr (r=- 0.13,<i> P</i>=0.084) was reported.<span style="font-size:10.0pt"></span></span><br> <span style="line-height:14pt"><b><i><span style="color:blue">Conclusion</span></i></b><i><span style="color:blue">:</span></i> Compared to the control group, CKD and AKI patients showed greater levels of endothelial dysfunction as evidenced by lower brachial artery FMD. However, the FMD technique did not appear to be a practical method in differentiating CKD and AKI in patients presenting with uremia for the first time.<span style="font-size:10.0pt"></span></span></span></span><br> &nbsp; Acute kidney injury, chronic kidney disease, endothelium, endothelial dysfunction , flow-mediated dilation 668 675 http://caspjim.com/browse.php?a_code=A-10-2773-1&slc_lang=en&sid=1 Sima Fallah Arzpeyma simafallaharzpeyma@gmail.com 100319475328460044883 100319475328460044883 Yes Razi Clinic Research Development Center, Guilan University of Medical Sciences, Rasht, Iran Elham Ramezanzadeh rz.elham58@gmail.com 100319475328460044884 100319475328460044884 No Razi Clinic Research Development Center, Guilan University of Medical Sciences, Rasht, Iran Azin Vakilpour azinvkp@gmail.com 100319475328460044885 100319475328460044885 No Cardiovascular Diseases Research Center, Department of Cardiology, Heshmat Hospital, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran Mohammadsadegh Abedi abedisadegh.tums@gmail.com 100319475328460044886 100319475328460044886 No Razi Clinic Research Development Center, Guilan University of Medical Sciences, Rasht, Iran. Soheil Hassanipour soheil.epid@gmail.com 100319475328460044887 100319475328460044887 No Cardiovascular Diseases Research Center, Department of Cardiology, Heshmat Hospital, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran