Nephrolithiasis among male patients with newly diagnosed gout.
BACKGROUND
An elevated serum urate level is recognised as a cause of gouty arthritis and uric acid stone. The level of serum uric acid that accelerates kidney stone formation, however, has not yet been clarified. This study aimed to find out if a high serum urate level is associated with nephrolithiasis.


METHODS
Patients were recruited from the rheumatology clinic of Taipei City Hospital (Renai and Zhongxing branches) in Taiwan from March 2015 to February 2016. A total of 120 Chinese male patients with newly diagnosed gout and serum urate concentration of >7 mg/dL and no history of kidney stones were divided into two groups according to their serum urate level: <10 mg/dL (group 1, n=80) and ≥10 mg/dL (group 2, n=40). The mean body mass index, blood urea nitrogen level, creatinine level, urinary pH, and kidney ultrasonography were compared between the two groups.


RESULTS
There were no significant differences in blood urea nitrogen or creatinine level between the two groups. The urine pH in both groups was similar and not statistically significant. Kidney stone formation was detected via ultrasonography in 6.3% (5/80) and 82.5% (33/40) of patients in groups 1 and 2, respectively (P<0.05).


CONCLUSIONS
A serum urate level of ≥10 mg/dL may precipitate nephrolithiasis. Further studies are warranted to substantiate the relationship between serum urate level and kidney stone formation.
Department of Immunology and Rheumatology, Taipei City Hospital-Zhongxing Branch, Taiwan.|Department of Pediatrics, Taipei City Hospital-Renai Branch, Taiwan.
K S
KS
Wan
Department of Urology, Taipei City Hospital-Zhongxing Branch, Taiwan.|Fu Jen Catholic University School of Medicine, Taiwan.
C K
CK
Liu
Department of Urology, Taipei City Hospital-Zhongxing Branch, Taiwan.
M C
MC
Ko
Department of Urology, Taipei City Hospital-Zhongxing Branch, Taiwan.
W K
WK
Lee
Department of Pediatrics, Taipei City Hospital-Renai Branch, Taiwan.
C S
CS
Huang
D000328:Adult; D015210:Arthritis, Gouty / Q000097:blood* / Q000150:complications*; D001806:Blood Urea Nitrogen; D003404:Creatinine / Q000097:blood; D006801:Humans; D007669:Kidney Calculi / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D013624:Taiwan; D062606:Tertiary Care Centers; D014463:Ultrasonography; D014527:Uric Acid / Q000097:blood*
D014527:Uric Acid; D003404:Creatinine
Gout; Nephrolithiasis; Uric acid