An observation on the composition and recurrence of urinary calculi.

Seven hundred patients with 735 urinary calculi were studied for the compositions of calculi by infrared analysis and for stone recurrence. Of these 700 cases, 422 cases were possible to follow up, and 250 cases have had no further stone; 138 cases experience recurring stones, and 34 cases had multiple stones. The length of follow-up period was 1-19 years averaging 8 years, 8 months. 41.2% of patients with calcium oxalate-calcium phosphate calculi had stones recurrently, and although there was some variation of recurrence rates for patients with various proportions of oxalate to phosphate in the calculi, it was impossible to predict the tendency of recurrence by these proportions. The stone recurrence was noted in 38.6% of patients with magnesium ammonium phosphate calculi, in 38.9% with mixed magnesium ammonium phosphate-calcium oxalate calculi, in 55.6% with uric acid calculi, and in 50% with cystine calculi.