Analysis of urinary calculi by chemical methods.

Two hundred twelve samples from 90 stones obtained from one hundred consecutive children with bladder stone disease (BSD) were analysed by qualitative and quantitative chemical methods. Majority (72%) of the stones were spherical in shape while 51% had mammilated surface. Children in older age group had heavier stones (P <0.05). The calculi were predominantly of mixed type (88.9%). Calcium oxalate was the commonest (97.7%) compound detected by qualitative chemical method. The central portion of calculi showed a significantly higher (P <0.02) occurrance of ammonium urate compared to the surface. Uric acid was present in surface layer in significantly higher (P <0.05) number in patients with uninfected urine. On quantitative analysis calcium and oxalate occurred in significantly higher (P <0.01) percentage in surface layers, while urate occurred more frequently (P <0.05) in the central portion of calculi. On comparing the two chemical methods of stone analysis, a good agreement was seen in the detection of calcium, oxalate and urate but phosphate was missed in 39% samples by the qualitative method and in 10% samples by quantitative method (JPMA 34 :147, 1984).