| Objective To study the composition of urinary stones,and assess the mechanisms of stone nucleation and aggregation.Methods 40 cases of integrated urinary tract stones of which diameter are more than 0.8cm were removed from the patients. All the stones were cut perpendicularly to the longer and shorter axis. Samples were selected from the nuclear, internal and external layers of each stone. All the fragments were used FTIR (Fourier transform infrared spectroscopy) method for qualitative and quantitative analysis, and then investigate the difference of the composition among the nuclear, internal and external layers of the different kinds of stones.Results Mixed stones were found in 25 cases of CaOx (calcium oxalate) stones (>50%) and 10 cases of CaP (calcium phosphate) stones (50%). 5 cases of UA (uric acid) calculus are pure stone (the percent of the composition >95%). And we found the contents of CaOx and CA.AP (carbapatite) crystals in different layers of the mixed stones were fairly variable. The content of CA.AP in the nuclear layers was higher than that of the outer layers (32.0%vs6.8%, P<0.05), while the content of CaOx was lower in the inner layers (57.6%vs86.6%, P <0.05) in CaOx stones. The content of CA.AP in the nuclear layers was higher than that of the outer layers (74.0%vs48.0%, P<0.05), while the content of CaOx was lower in the inner layers (7.0%vs40.0%, P<0.05) in CaP stones. There are no differences between the different layers of the uric acid stones.Conclusions Using FTIR for the qualitative and quantitative analysis of urinary stones helps us to understand the formation mechanism of urolithiasis and to choose appropriate treatments and prevention. CA.AP crystal is prone to be found in the nuclear layer, while CaOx tends to exist in the external layer of the mixed stone. Urinary tract infection and metabolize play and different role in different phase of evolution of the stones. |
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