title: Ammonium acid urate urolithiasis in Japan.
abstract: OBJECTIVE
  Ammonium acid urate (AAU) calculi are a rare urolithiasis in developed countries but are endemic in developing countries. We assessed the features of AAU urolithiasis in Japanese patients.
  
  
  METHODS
  We reviewed hospital charts of patients with urolithiasis who were treated with extracorporeal shock wave lithotripsy and endourological procedures at Sagamidai Hospital (Kanagawa, Japan) from January 1992 to December 2001. On the basis of the results of stone analysis with an infrared spectrophotometer, AAU stones were found.
  
  
  RESULTS
  Of 8664 urolithiasis that we reviewed, 33 calculi (0.38%) from 29 patients contained AAU crystals. From crystallographic findings, we defined two types of AAU-containing stones: pure and mixed AAU urolithiasis. Pure AAU urolithiasis were seen in 13 stones from 10 patients and mixed AAU in 20 stones from 19 patients. We found significant differences between the groups: the pure AAU group predominantly consisted of young, thin women and the mixed group consisted of middle-aged men. Laboratory findings showed trends of low levels of serum protein, potassium, and urine pH in the pure AAU group.
  
  
  CONCLUSIONS
  Because each type of AAU urolithiasis is associated with different patient characteristics and pathophysiological features, it is important to understand the type of AAU urolithiasis in patients with calculi.
authors.affiliation: Department of Urology, Jikei University School of Medicine, Tokyo, and Department of Urology, Sagamidai Hospital, Kanagawa, Japan. hkuruma@jikei.ac.jp
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Kuruma
authors.forename: Takashi
authors.initials: T
authors.lastname: Arakawa
authors.forename: Seiichi
authors.initials: S
authors.lastname: Kubo
authors.forename: Toru
authors.initials: T
authors.lastname: Hyodo
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Matsumoto
authors.forename: Takefumi
authors.initials: T
authors.lastname: Satoh
authors.forename: Shin
authors.initials: S
authors.lastname: Egawa
authors.forename: Shiro
authors.initials: S
authors.lastname: Baba
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D012727:Sex Characteristics; D014527:Uric Acid / Q000378:metabolism*; D014545:Urinary Calculi / Q000453:epidemiology* / Q000378:metabolism* / Q000473:pathology
chemical_list: D014527:Uric Acid