[Clinical features of passed calcium oxalate monohydrate and dihydrate stones].

105 calcium oxalate stones (calcium oxalate content greater than calcium phosphate) which were passed spontaneously from 1983 to 1988 were studied by infrared analysis and divided into 51 COM stones and 54 COD stones according to the content of calcium oxalate monohydrate (COM) and dihydrate (COD). The appearance and consistency of 11 COM stones (21.6%) were like those of the typical COD stone, although the dark brown, firm core suggesting the typical COM stone was found in 3 COD stones (5.6%). The content of calcium phosphate was higher in COD stones than in COM stones (P < 0.01). There was no significant difference between the weights of 51 COM and 54 COD stones. However, regarding 73 stones < 100 mg in weight, COD stones were heavier than COM stones (p < 0.05); 48.0 +/- 23.8 and 35.4 +/- 23.2 mg (mean +/- standard deviation) for 38 COD and 35 COM stones respectively. COM stones were found in older patients than COD stones (p < 0.05); 45.2 +/- 12.8 and 39.9 +/- 11.2 years old for 51 COM stone patients and 54 COD stone patients. There was no significant difference in the sex distribution and the number of patients with a history of stone(s) between COM and COD stone patients. Fifty-three patients were followed at yearly intervals without any prophylactic treatment for stone recurrence. The follow up periods were 37.6 +/- 27.1 and 32.1 +/- 20.9 mos. for 25 COM and 28 COM stone patients respectively.(ABSTRACT TRUNCATED AT 250 WORDS)