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World J Clin Pediatr. May 8, 2015; 4(2): 25-29
Published online May 8, 2015. doi: 10.5409/wjcp.v4.i2.25
Pyuria in patients with Kawasaki disease
Toru Watanabe
Toru Watanabe, Department of Pediatrics, Niigata City General Hospital, Chuo-ku, Niigata City 950-1197, Japan
Author contributions: Watanabe T solely contributed to this paper.
Conflict-of-interest: The author has no conflict of interest.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Toru Watanabe, MD, PhD, Department of Pediatrics, Niigata City General Hospital, 463-7 Shumoku, Chuo-ku, Niigata City 950-1197, Japan. twata@hosp.niigata.niigata.jp
Telephone: +81-25-2815151 Fax: +81-25-2815169
Received: November 19, 2014
Peer-review started: November 20, 2014
First decision: December 26, 2014
Revised: January 8, 2015
Accepted: February 4, 2015
Article in press: February 9, 2015
Published online: May 8, 2015
Abstract

Kawasaki disease (KD) is an acute, febrile vasculitis that predominantly develops in children ≤ 5 years of age and can lead to multiple organ injuries including the kidneys. Of these injuries, pyuria is a common feature of patients with KD, occurring in 30%-80% of patients. Sterile pyuria is most common in KD patients ≤ 1 year of age. KD patients with sterile pyuria exhibit more severe inflammatory reactions and may have sub-clinical renal injuries. Sterile pyuria in KD is associated with mononuclear cells (not neutrophils) in the urine. Although sterile pyuria in KD was at one time thought to be due to urethritis caused by a non-specific vasculitis of the urethra, recent studies suggest that sterile pyuria in KD originates from the urethra, the kidney as a result of mild and sub-clinical renal injuries, and/or the bladder due to cystitis. Pyuria is not always sterile in KD, but can result from a urinary tract infection (UTI). As causative pathogens, Escherichia coli and Klebsiella oxytoca have been reported. The clinical phenotypes do not differ between those with or without UTI. Because some KD patients with UTIs have urinary tract abnormalities such as vesicoureteral reflux, a complete UTI workup including renal ultrasound, voiding cystourethrogram and/or dimercaptosuccinic acid renal scan recommended in KD patients with UTIs.

Keywords: Sterile pyuria, Kidney involvement, Urinary tract infection, Kawasaki disease, Vasculitis

Core tip: Pyuria is a common feature of patients with Kawasaki disease (KD), occurring in 30%-80% of patients. KD patients with pyuria exhibit more severe inflammatory reactions and may have sub-clinical renal injuries. Pyuria in KD originates from the urethra, the kidney as a result of mild and sub-clinical renal injuries, and/or the bladder due to cystitis. Pyuria is not always sterile in KD, but can result from a urinary tract infection (UTI). Because some KD patients with UTIs have urinary tract abnormalities, a complete UTI workup including renal ultrasound, voiding cystourethrogram and/or dimercaptosuccinic acid renal scan is recommended in KD patients with UTIs.