Community Based Cross-sectional Investigation Of Kidney Stone Incidence And Urine Composition Analysis In Patients With Kidney Stones

Part Ⅰ Application of liquid chromatography in the determination of oxalic acid and citric acid in urine ObjectiveThe purpose of this study is to establish a simple and reliable high performance liquid chromatography(HPLC)method for the simultaneous determination of oxalic acid and citric acid in urine,which can be applied to the determination of urine samples of patients with kidney stones.MethodsThe blank samples were injected according to the sample pretreatment steps to observe whether there was interference in the retention time of the analytes;six urine samples from different sources were selected and injected according to the sample pretreatment steps to observe whether there was overlap in the retention time of the interfering compounds and the analytes.The samples were determined according to the standard curve and standard addition steps,and linear fitting was carried out with the concentration of the analyte as the abscissa and the peak area of the analyte as the ordinate.The quality control samples of low,medium and high concentrations were determined.Each batch of samples with the same concentration was determined 5samples per day,and 3 batches were determined continuously.According to the standard curve drawn for each batch,the sample concentration was calculated and compared with the actual added concentration,and the accuracy of three concentrations,intra batch and inter batch precision were calculated.ResultsIn the aspect of specificity,the retention time of oxalic acid and citric acid in urine samples were 9.7 ± 0.2min and 10.9 ± 0.2min,respectively.In the blank sample,oxalic acid and citric acid had no interference in the retention time,and oxalic acid and citric acid in urine samples could be separated from the impurity baseline(resolution > 1.5),indicating that the method had good specificity.In terms of sensitivity,the detection limit and quantitation limit of oxalic acid were 0.6mg/l and 3.1mg/l respectively,and the linear range was 3.1-50mg/l;the detection limit and quantitation limit of citric acid were7.1mg/l and 156 mg / L respectively,and the linear range was 156-2500 mg / L.The results showed that the detection method had good sensitivity,and the linear range could meet the daily detection needs of oxalic acid and citric acid in urine.The correlation coefficient R2 of standard curve and standard addition curve of oxalic acid and citric acid was greater than 0.999.The results showed that both of them had good linearity in their range.In terms of accuracy and precision,the intra-and inter batch precisions of oxalic acid and citric acid were less than 5%,which met the requirements of less than 15% in ICH methodology validation guidelines;the accuracy of oxalic acid and citric acid was in the range of 97.1-101.8%,which met the requirements of 85-115% in ICH methodology validation guidelines;the method showed good accuracy and precision,as shown in Table 1 The method is reliable.ConclusionIn this study,we established a method for the determination of oxalic acid and citric acid in urine by liquid chromatography.The method is simple and has good specificity,sensitivity,accuracy and precision.It has a good application prospect in the diagnosis of urinary calculi and the prediction of stone composition.Part Ⅱ Cross sectional investigation and risk factors analysis of upper urinary tract stones among residents in a community of Hainan ProvinceObjective To explore the epidemiological characteristics and influencing factors of upper urinary tract stones in a town of Danzhou City,Hainan Province,and to further analyze the indicators that can be used to predict the occurrence of upper urinary tract stones.Methods This study adopts the method of cross-sectional survey,takes the permanent residents who have lived in a town in Danzhou City of Hainan Province as the research object,selects them according to the inclusion criteria and exclusion criteria,and uses the self-made questionnaire form for data collection.The contents of the survey mainly include diet survey,general demographic characteristics survey,medical history collection,etc.;at the same time,physical examination,laboratory examination and ultrasound examination were carried out to measure the physiological and biochemical indexes of the subjects.Results A total of 388 subjects were included in this study.After the start of the study,5 subjects voluntarily withdrew.Finally,a total of 383 valid questionnaires were collected,of which 379 received B-ultrasound examination.A total of 138 patients with upper urinary tract stones were found,and the prevalence rate was 36.4%.Among them,77 patients had unilateral kidney stones,19 patients had bilateral kidney stones,2 patients had ureteral stones,and 40 patients had renal crystal / calcification.The prevalence rates of these four parts were 20.3%,4.9%,0.5% and 10.6% respectively.The survey showed that the prevalence rate of upper urinary tract stones was 47.3%(69 / 146)in males and 29.6%(69 / 233)in females,which was significantly higher in males than in females(= 12.072,P = 0.001).The highest age group was 60-69 years old,and the prevalence rate was 42.4%.Reviewing the past history of the subjects,it was found that the stone group had a higher proportion of previous history of upper urinary tract stones(P = 0.000)and spontaneous expulsion of stones(P = 0.015)than the control group,and the difference was statistically significant.In laboratory examination,the serum uric acid level of the stone group was higher than that of the control group(P = 0.010),the 24-hour urine volume of the stone group was lower than that of the control group(P = 0.030),and the 24-hour urine Ca / Cr(P = 0.008)and 24-hour urine Ca / CIT(P = 0.017)of the stone group were higher than those of the control group.Multivariate logistic regression analysis showed that the risk of upper urinary calculi was increased in patients with higher 24-hour urinary Ca / CIT(or = 6.437,95% CI: 1.226-33.784),and increased in patients with previous history of upper urinary calculi(or = 2.751,95% CI: 1.492-5.072).Equil2 software was used to analyze the relative supersaturation of urine.It was found that the relative supersaturation of calcium oxalate(SSCa Ox)in the stone group was higher than that in the control group(P = 0.021).Calcium oxalate crystals in the stone group tended to be supersaturated,while calcium oxalate crystals in the control group tended to be dissolved(DGCa Ox,P = 0.008).Further correlation analysis and linear regression analysis between SSCa Ox,DGCa Ox and 24-hour urine biochemical indexes showed that 24-hour urine calcium,urine oxalic acid,urine volume,urine citric acid,urine p H,urine phosphorus,urine sodium and urine chlorine were significant influencing factors of SSCa Ox,and 24-hour urine calcium,urine volume,urine oxalic acid,urine p H,urine citric acid and urine phosphorus were significant influencing factors of DGCa Ox.Conclusion In this study,we investigated the residents in Danzhou City,Hainan Province,and found that the prevalence of upper urinary tract stones in this area was significantly higher than the national average level.Men and middle-aged and elderly people were high-risk population.A number of blood and urine biochemical indicators were of certain significance in predicting the occurrence of stones.The 24-hour urine relative supersaturation tool was of great value in predicting the occurrence and composition of stones.In clinical practice,we can further study the above factors and carry out prospective cohort study to clarify the specific influence mechanism of each factor on the incidence of stones,so as to provide guidance for the prevention and treatment of upper urinary tract stones.