Mixed Uric Acid Research Articles

Kidney Stones of Type I vs. Type II Diabetic Patients: Are There Any Differences?

Background: This study highlighted the differences between the biochemical compositions of urinary stones from patients with type 1 diabetes versus those with type 2 diabetes. Materials and Methods: This study included patients diagnosed with kidney stones and diabetes who were referred to the Urological Clinic of the Dr. C. I. Parhon Hospital in Iasi from April 2017 to April 2024. We analyzed the spectroscopic stone composition from 128 lithiasis patients treated in our Clinic. In the current study, the distribution of the biochemical composition of stones varied significantly between diabetic patients with type 2 diabetes, who formed primarily mixed uric acid stones, and diabetic patients with type 1 diabetes, who mainly developed pure uric acid stones (p < 0.001). Patients with uric acid stones had significantly higher mean creatinine values than the other stone types (p < 0.001). Urinary pH levels were abnormal for all biochemical subtypes of stones, indicating acidic urine. However, patients with uric acid stones had lower pH values than the group average. From the Kaplan–Mayer analysis, patients with pure uric acid stones had a shorter time to stone recurrence compared to patients with other biochemical types identified. Conclusions: These findings, which highlight the prevalence of pure uric acid stones in patients with type 1 diabetes and the impact of this on the strategy for dissolving pure stones, represent a significant advancement in understanding urinary lithiasis in diabetic patients.

Using computed tomography to predict in vivo stone chemical composition

OBJECTIVES. Several authors hypothesized the usefulness of the non-contrast helical computed tomography (NCHCT) with the determination of stone Hounsfield Unit (HU) values in order to predict urinary stone compositions. Preoperative knowledge of stone composition might be interesting in pre-operative decision-making process. The aim of this study was to evaluate the possible correlation between stone chemical composition and correspondent stone HU value in an in-vivo experience. METHODS. Forty patients with urinary stones were preoperatively studied with abdominal NCHCT, where stone HU values were reported. Stone chemical composition was obtained in each patient, using the colorimetric method. The HU value of each stone was compared with the correspondent chemical analysis. Results. The median HU values of calcium oxalate (n=10), mixed calcium oxalate and phosphate (n=19), calcium phosphate (n=2), uric acid (n=6) and mixed uric acid and calcium oxalate (n=3) stones were 1060 HU [interquartile range (IQR) 743.75-1222.5]; 900 HU (IQR 588.5-1108.5); 774 HU (range 720-828); 371 HU (IQR 361.25-436.25) and 532 HU (range 476-626), respectively. CONCLUSIONS. Our results confirmed a statistically significant difference of the HU values between calcium and pure uric acid calculi, suggesting a correlation between stone chemical composition and CT-density. Hounsfield unit.

A comparison of the metabolic profiles of diabetic and non-diabetic uric acid stone formers

Introduction: The aim of this study was to compare the metabolic profiles of diabetic and non-diabetic patients with uric acid stones to understand whether preventive strategies should be tailored to reflect different causative factors.Methods: The results of the metabolic evaluation of patients with uric acid stones identified prospectively from the Metabolic Stone Clinic at St. Joseph’s Hospital, London, Canada were reviewed. Information included patients’ clinical histories, 24 hour urine collections, blood chemistry and stone analysis.Results: Complete data were obtained from 68 patients with uric acid stones. Twenty-two patients had diabetes. There were no statistically significant differences in mean age, body mass index, or history of gout. Among diabetics, pure uric acid stones were identified in 14 patients (63%) and mixed uric acid in 8 (36%). Pure uric acid stones were more common in the diabetic cohort (63% vs. 46%, p = 0.16). Urine pH, serum and urine uric acid levels and 24-hour urine volumes were similar in both groups. The diabetic group had an increased average oxalate excretion (424 μmol/d vs. 324 μmol/d, p = 0.003).Conclusion: The exact etiological basis for the higher oxalate excretion in diabetic uric acid stone formers is unclear. Whether this is a metabolic feature of diabetes, due to dietary indiscretion or the iatrogenic consequence of dietary advice requires further investigation.

A comparison of the metabolic profiles of diabetic and non-diabetic uric acid stone formers

The aim of this study was to compare the metabolic profiles of diabetic and non-diabetic patients with uric acid stones to understand whether preventive strategies should be tailored to reflect different causative factors. The results of the metabolic evaluation of patients with uric acid stones identified prospectively from the Metabolic Stone Clinic at St. Joseph's Hospital, London, Canada were reviewed. Information included patients' clinical histories, 24 hour urine collections, blood chemistry and stone analysis. Complete data were obtained from 68 patients with uric acid stones. Twenty-two patients had diabetes. There were no statistically significant differences in mean age, body mass index, or history of gout. Among diabetics, pure uric acid stones were identified in 14 patients (63%) and mixed uric acid in 8 (36%). Pure uric acid stones were more common in the diabetic cohort (63% vs. 46%, p = 0.16). Urine pH, serum and urine uric acid levels and 24-hour urine volumes were similar in both groups. The diabetic group had an increased average oxalate excretion (424 μmol/d vs. 324 μmol/d, p = 0.003). The exact etiological basis for the higher oxalate excretion in diabetic uric acid stone formers is unclear. Whether this is a metabolic feature of diabetes, due to dietary indiscretion or the iatrogenic consequence of dietary advice requires further investigation.

IMPROVING THE INTERPRETATION OF URETEROSCOPIC BIOPSIES: USE OF BOUIN'S FIXATIVE

Introduction: The aim of this study was to compare the metabolic profiles of diabetic and non-diabetic patients with uric acid stones to understand whether preventive strategies should be tailored to reflect different causative factors. Methods: The results of the metabolic evaluation of patients with uric acid stones identified prospectively from the Metabolic Stone Clinic at St. Joseph’s Hospital, London, Canada were reviewed. Information included patients’ clinical histories, 24 hour urine collections, blood chemistry and stone analysis. Results: Complete data were obtained from 68 patients with uric acid stones. Twenty-two patients had diabetes. There were no statistically significant differences in mean age, body mass index, or history of gout. Among diabetics, pure uric acid stones were identified in 14 patients (63%) and mixed uric acid in 8 (36%). Pure uric acid stones were more common in the diabetic cohort (63% vs. 46%, p 0.16). Urine pH, serum and urine uric acid levels and 24-hour urine volumes were similar in both groups. The diabetic group had an increased average oxalate excretion (424 mol/d vs. 324 mol/d, p 0.003). Conclusion: The exact etiological basis for the higher oxalate excretion in diabetic uric acid stone formers is unclear. Whether this is a metabolic feature of diabetes, due to dietary indiscretion or the iatrogenic consequence of dietary advice requires further investigation.

Targeted dual-energy single-source CT for characterisation of urinary calculi: experimental and clinical experience

To assess the accuracy of targeted dual-energy single-source multi-detector CT (MDCT) for characterisation of urinary calculi. For proof of principle, 71 ex-vivo calculi underwent single-source 256-slice MDCT. Low-dose CT was performed in 154 patients with suspected urinary calculi. In 104 patients with urinary calculi targeted dual-energy imaging within one breath-hold was added. 46 patients with sufficient material for infrared-spectroscopy were analysed. Potential anatomical misregistrations between 80- and 140-kV(p)-images and HU-values were measured. DEIs (dual-energy-indices) were compared with the standard of reference. Effective doses were calculated. In 26 of 46 patients no misregistration was present. Mean deviations were 2.7 mm in the z-axis (16 patients) and 4.3 mm in the axial plane (10 patients). The DEIs were 0.018 ± 0.016 for uric acid (UA), 0.035 ± 0.015 for mixed UA and 0.102 ± 0.015 for calcified stones in-vitro and 0.017 ± 0.002 for UA, 0.050 ± 0.019 for mixed UA and 0.122 ± 0.024 for calcified calculi in-vivo. Significant differences were noted among calcium, mixed UA and UA stones (p < 0.05). For the low-dose examination mean effective dose was 3.11 mSv. Targed dual-energy resulted in an extra dose of 1.84 mSv (additional 59.1%). Targeted dual-energy imaging within one breath-hold is feasible for characterisation of urinary calculi using single-source MDCT allowing minimal anatomical discordance.

Dual-source dual-energy CT for the differentiation of urinary stone composition: preliminary study

Objective To evaluate dual-source dual-energy CT(DSCT) for the differentiation of urinary stone composition in vitro. Methods Ninety-seven urinary stones were obtained by endoscopic lithotripsy and scanned using dual-source dual-energy CT. The stones were divided into six groups according to infrared spectroscopy stone analysis: uric acid ( UA ) stones ( n = 10 ), cystine stones ( n = 5 ), struvite stones( n = 6), calcium oxalate ( CaOx ) stones ( n = 22 ), mixed UA stones ( n=7 ) and mixed calcium stones(n=47). Hounsfield units (HU) of each stone were recorded for the 80 kV and the 140 kV datasets by hand-drawing method. HU difference, HU ratio and dual energy index ( DEI ) were calculated and compared among the stone groups with one-way ANOVA. Using dual energy software to determine the composition of all stones, results were compared to infrared spectroscopy analysis. Results There were statistical differences in HU difference [(-17±13), (229±34),(309 ±45), (512 ±97), (201±64)and (530±71) HU respectively], in HU ratio (0.96±0.03, 1.34 ±0.04, 1.41 ±0.03, 1.47 ±0.03,1.30±0.07, and 1.49 ±0.03 respectively), and DEI( -0.006 ±0.004, 0.064 ±0.007, 0.080 ±0. 007, 0. 108±0.011 ,0. 055 ±0.014 and 0. 112 ±0.008 respectively ) among different stone groups(F=124. 894,407.028, 322. 864 respectively, P ＜0. 01 ). There were statistical differences in HU difference,HU ratio and DE1 between UA stones and the other groups( P ＜ 0. 01 ). There were statistical differences in HU difference, HU ratio and DEI between CaOx or mixed calcium stones and the other four groups (P＜0. 01 ). There was statistical difference in HU ratio between cystine and struvite stones ( P ＜ 0. 01 ). There were statistical differences in HU difference, HU ratio and DEI between struvite and mixed UA stones (P＜0. 05 ). Dual energy software correctly characterized 10 UA stones, 4 cystine stones, 22 CaOx stones and 6 mixed UA stones. Two struvite stones were considered to contain cystine. One cystine stone, 1 mixed UA stone, 4 struvite stones and 47 mixed calcium stones were considered to contain oxalate. Conclusions DSCT has the ability to differentiate urinary stone composition in vitro. With dual energy software, the UA, cystine and mixed UA stones can be differentiated from other types of stones. Key words: Urinary calculi; Tomography,X-ray computed

Using Computed Tomography to Predict in Vivo Stone Chemical Composition

Objectives Several authors hypothesized the usefulness of the non-contrast helical computed tomography (NCHCT) with the determination of stone Hounsfield Unit (HU) values in order to predict urinary stone compositions. Preoperative knowledge of stone composition might be interesting in pre-operative decision-making process. The aim of this study was to evaluate the possible correlation between stone chemical composition and correspondent stone HU value in an in-vivo experience. Methods Forty patients with urinary stones were preoperatively studied with abdominal NCHCT, where stone HU values were reported. Stone chemical composition was obtained in each patient, using the colorimetric method. The HU value of each stone was compared with the correspondent chemical analysis. Results The median HU values of calcium oxalate (n=10), mixed calcium oxalate and phosphate (n=19), calcium phosphate (n=2), uric acid (n=6) and mixed uric acid and calcium oxalate (n=3) stones were 1060 HU [interquartile range (IQR) 743.75–1222.5]; 900 HU (IQR 588.5–1108.5); 774 HU (range 720–828); 371 HU (IQR 361.25–436.25) and 532 HU (range 476–626), respectively. Conclusions Our results confirmed a statistically significant difference of the HU values between calcium and pure uric acid calculi, suggesting a correlation between stone chemical composition and CT-density. Hounsfield unit