[Clinical assessment of ammonium acid urate urinary calculi]

We investigated the patients with ammonium acid urate (AAU) calculi in relation to dietary history, habit and lifestyle. From April, 2002 to March, 2009, AAU calculi were found in 9 patients (0.66) out of 1,365 cases of stones. Three cases were pure, and 6 were mixed stones. We examined the risk factor of this stone generation, "continuation of malnutrition and dehydration" were seen in 5, "continuing urinary tract infection" was seen in 4 and "continuation of super-saturation of uric acid in urine" was seen in 3 cases. All the patients with "continuation of malnutrition and dehydration" were women, and 4 patients had a history of severe body weight loss. 2 patients were dieting consciously, and the other 2 were eating a poorly balanced diet unconsciously. One patient had no notable past history, but malnutrition was detected in blood examination. It is suggested that AAU calculi is generated even by dieting at a usual level. Compared with the report in the United States, obesity and inflammatory bowel disease were not major risk factors, and "continuation of malnutrition and dehydration" is the major factor in Japan.