Posterior nutcracker phenomenon with Down syndrome

* Corresponding author. Division of Nephrology, The Catholic University of 07345, Korea. E-mail address: [email protected] (S Chung). http://dx.doi.org/10.1016/j.krcp.2015.10.001 2211-9132/Copyright © 2015. The Korean Society of Nephrology. Published license (http://creativecommons.org/licenses/by-nc-nd/4.0/). pale appearance. Laboratory investigations revealed the hemoglobin and hematocrit levels were 6.2 g/dL and 22.5%, respectively. Although his family witnessed another episode of gross hematuria few weeks before admission, urinalysis on admission showed no evidence of hematuria. An initial abdominal ultrasonography showed normal size and echogenicity of both kidneys without definite focal lesion. However, computed tomography of the abdomen revealed entrapment of a retroaortic left renal vein between the aorta and the vertebral column (Fig.1), indicating posterior nutcracker syndrome. After consultation, it was decided that he should undergo conservative follow-up. The retroaortic left renal vein, also known as posterior nutcracker syndrome, is a rare congenital phenomenon. Because patients with Down syndrome usually have a decreased risk for vascular anomalies because of increased vascular endothelial growth factor inhibitors from an extra copy of chromosome 21, posterior nutcracker syndr-