RELATIONSHIP BETWEEN CHEMICAL COMPONENT OF CALCULI AND ITS PHYSICOCHEMICAL PROPERTIES, PROTEIN COMPOSITION AND BLOOD URIC ACID CONCENTRATION IN PATIENTS WITH UPPER URINARY CALCULI

Lei Xia^#, Hanqing Xuan^#, Yang Cao, Zhebin Du, Hai Zhong, Qi Chen^*

Department of Urology, Ren Ji Hospital, School of Medicine Shanghai Jiao Tong University, Shanghai, PR China

Objective: This study explores the relationship between the chemical components of calculi and the physicochemical properties of urine, protein composition and blood uric acid concentration in patients with upper urinary calculi. 

Methods: The observation group was comprised of 160 patients with upper urinary calculi who needed lithotripsy through ureteroscopy and percutaneous nephrolithotomy in our urology department from August 2018 to August 2019. For the control group, 30 healthy people were examined at our hospital. Then, 3 ml of fasting venous blood was collected from preoperative patients and the control group. The uric acid level in all patients was detected using uricase, and 24 h urine samples were collected from all subjects. Calcium, phosphorus, magnesium, potassium and uric acid in urine were detected using an automatic analyser, and albumin (mAlb), α1-microglobulin (α1-MG), β2-microglobulin (β2-MG) and transferrin (TRF) were detected using an automatic special protein analyser. Also, stone samples were collected from the patients after the operation, and the chemical components of calculi in all patients were detected by the type LIIR-20 infrared spectrometer. The relationship between the chemical components of calculi and the physicochemical properties of urine, protein composition and blood uric acid concentration in patients with upper urinary stones was investigated. 

Results: A total of 160 patients with upper urinary calculi that were detected by an infrared spectrum analyser participated in the study: 83 patients (51.88%) had oxalate-based stones, 35 (21.88%) had phosphonate-based stones, 23 (14.38%) had uric acid-based stones and 19 (11.88%) had apatite-based stones. All patients with upper urinary calculi were divided into an oxalate group, phosphate group, uric acid group and apatite group according to the component of the calculi. Compared with the 24 h urine physicochemical properties of the control group, it was found that the pH of the urine in the phosphate group and apatite group was significantly higher than that in the control group, the urine pH of patients in the uric acid group and the oxalate group was significantly lower than that in the control group, and the difference was statistically significant (P<0.05). Also, the urine volume of patients in the phosphate group, apatite group, uric acid group and oxalate group was significantly lower than that in the control group, and the difference was statistically significant (P<0.05). Furthermore, the urine phosphate level in the phosphate group was significantly lower than that in the control group, and the difference was statistically significant (P<0.05). The urine magnesium in the uric acid group was also significantly higher than that in the control group, and it was significantly lower in the oxalate group than in the control group (P<0.05). The levels of β2-MG and α1-MG in the oxalate group were significantly higher than those in the control group, and the difference was statistically significant (P<0.05). There was no significant difference in urine protein levels in other groups compared with the control group (P>0.05). The levels of uric acid of urine and serum in the oxalate group and uric acid group were significantly higher than those in the control group, and the differences were statistically significant (P<0.05). There was no significant difference in the uric acid levels of urine and serum in other groups compared with the control group (P>0.05). The Pearson correlation analysis showed that β2-MG was positively correlated with oxalate and urinary calcium (all P<0.05) and negatively correlated with pH (P<0.01); uric acid was positively correlated with oxalate, urate and urinary calcium (P<0.05) and negatively correlated with pH (P<0.05); and α1-MG was positively correlated with oxalate and urinary calcium (P<0.05 or <0.01) and negatively correlated with pH (P<0.05). 

Conclusion: Oxalate calculi are the most common type of upper urinary calculi. The abnormal expression of uric acid and urinary protein in patients with upper urinary calculi is significantly related to the chemical components of the calculi and the physicochemical properties of urine.