Chronological variation in the chemical composition of upper urinary tract calculi.

From 1953 to 1984 upper urinary tract calculi obtained by operation or spontaneous discharge were analyzed by infrared spectroscopy. A review of the stone compositions for each 4-year interval from 1953 to 1984 showed a decreased incidence of magnesium ammonium phosphate-containing stones from 1961 and later. The incidence of these stones was approximately 20 per cent before 1960 and approximately 10 per cent after 1961, although the percentage increased again after 1973, especially in female patients. The decreased percentage after 1961 coincided with a decrease in the ratio of renal-to-ureteral stones. The development of antibiotics might have had an important role in the variation of stone compositions.