Sequential analysis of recurrent calcium calculi by infrared spectroscopy.

BACKGROUND: While the incidence of calcium urolithiasis increases, the precise mechanism of calcium oxalate stone formation is still controversial. Is the composition of a recurrent calcium oxalate stones always the same as previous ones? There are few reports that specifically address the question by study of sequential changes of the composition of recurrent calcium calculi.

METHOD: From our medical records 70 patients with a history of two or more recurrent episodes of calcium oxalate stone disease were selected and the analyses of 190 stones were reviewed. Infrared spectroscopic analysis was done using a Perkin Elmer 1740 spectrophotometer.

RESULTS: Calcium oxalate monohydrate were detected in 63 stones, calcium oxalate dihydrate in 12, calcium oxalate monohydrate mixed with dihydrate in 28, calcium oxalate monohydrate mixed with calcium phosphate in 30, calcium oxalate dihydrate mixed with calcium phosphate in 20, calcium oxalate monohydrate mixed with dihydrate and calcium phosphate in 20, calcium oxalate monohydrate mixed with dihydrate and calcium phosphate in 37. Alterations of stone components during follow-up were found in 43 stones from 40 patients. The shift of a main composition from calcium oxalate monohydrate to calcium oxalate dihydrate was found in 24 stones and vice versa in 19 stones.

CONCLUSIONS: Sequential changes of the compositions of recurrent calcium calculi are highly likely to occur with time in individual recurrent calcium stone formers. Calcium oxalate monohydrate was a most common component of the studied recurrent calcium stones.