Chemical analysis of post-lithotripsy stone fragments: a critical evaluation

A scheme for the chemical microanalysis of renal stone fragments recovered from urine voided immediately after lithotripsy has been developed and evaluated. The analytical procedure includes assay of calcium, magnesium, phosphate, oxalate and urate and has been applied to 78 such urine samples. Problems relating to co-existing crystalluria and blood and urine contaminants have been recognised and overcome. However, significant loss of all stone components due to fragment dissolution in urine prior to recovery was found to occur and was investigated. The distribution of stone components found in these analyses was similar to that seen in previous surveys of intact stones.