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Study on the pathogenesis and prevention strategies of kidney stones based on GC-MS combined with metabolic pathway analysis.

RATIONALE
Most kidney stone composition analyses include organic compounds, and only few organic volatile compounds have been reported.


METHODS
In the present study, a novel approach for studying the pathogenesis and prevention of kidney stones was established. First, common organic volatile compounds were detected using gas chromatography-mass spectrometry (GC-MS) in 137 kidney stone samples. The Kyoto Encyclopedia of Genes and Genomes database and MetaboAnalyst 5.0 software were then used to analyze the metabolic pathways associated with the development of kidney stones.


RESULTS
The metabolic pathway analysis of the common component cholesterol revealed that two metabolic pathways, the steroid biosynthesis pathway and primary bile acid biosynthesis pathway, were closely associated with the formation of kidney stones. The pretreatment process for stone analysis, including the solvent type, solvent volume, and extraction time, was optimized to improve the detection efficiency. The calibration curve was y = 756299x - 8000000, with the correlation coefficient (r) of 0.9992, which were obtained over the concentration range of 10-500 μg mL-1 of cholesterol. The recovery values of cholesterol ranged from 93.34% to 94.67%, 96.98% to 99.23%, and 87.27% to 93.00% when spiked with 0.75, 1.00, and 1.25 μg, respectively, with the relative standard deviation of no less than 3.18%. Finally, the content of common compounds was determined in 37 renal stone samples using the modified GC-MS method.


CONCLUSIONS
The common organic volatile compound in the kidney stone samples detected using GC-MS was cholesterol, and the steroid biosynthesis and primary bile acid biosynthesis pathways were determined to be closely associated with the formation of kidney stones. The GC-MS method for detecting cholesterol in kidney stones was optimized for efficiency and accuracy.