Ammonium acid urate urolithiasis in Japan

Abstract

Aim: 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.

Clinical study of ammonium acid urate urolithiasis

“…However, the incidence of AAU stones has been decreasing in most of the countries in the so‐called “endemic bladder stone belt” with gradual improvements in nutrition levels and public health education. At present, sporadic cases of AAU urolithiasis are unusual in industrialized countries, and the prevalence varies with different geographical areas; e.g., 0.3% in the United States [5], 0.38% in Japan [11], 0.7% in our study, and up to 0.75% in Norway [12]. In contrast, there are still abnormally high incidences of AAU stones in specific regions.…”

“…Hidetoshi et al. [11] reported that 70.0% of patients with pure AAU stones engaged in laxative abuse compared with 26.3% of patients with mixed stones. Incomplete biochemical urine tests and inadequate classification data might lead to inaccurate risk stratification.…”

Rotavirus gastroenteritis‐associated urinary ammonium acid urate crystals

“…Ammonium acid urate calculi are extremely rare renal stone components, found in only 0.38% of all urolithiasis patients in Japan . It is widely known that the presence of AAU calculi often coincides with underlying diseases such as urinary tract infection, anorexia nervosa, and laxative abuse . Endemic AAU urolithiasis, particularly bladder calculi in children, however, is evident in developing countries …”

“…6 It is widely known that the presence of AAU calculi often coincides with underlying diseases such as urinary tract infection, anorexia nervosa, and laxative abuse. [6][7][8] Endemic AAU urolithiasis, particularly bladder calculi in children, however, is evident in developing countries. 6,7,9 Recently, many cases of RV gastroenteritis-induced acute post-renal failure due to bilateral ureteric renal stone obstruction have been reported in Japan.…”

“…[6][7][8] Endemic AAU urolithiasis, particularly bladder calculi in children, however, is evident in developing countries. 6,7,9 Recently, many cases of RV gastroenteritis-induced acute post-renal failure due to bilateral ureteric renal stone obstruction have been reported in Japan. 3,4 Ashida et al suggested that most RV gastroenteritis-associated urinary tract calculi are AAU calculi.…”