Evaluation Of Stone Formers Research Articles

Risk of Symptomatic Kidney Stones After Kidney Donor Evaluation in Stone Formers

Risk of Symptomatic Kidney Stones After Kidney Donor Evaluation in Stone Formers

Prophylaxis of Recurrent Stone Disease in Outpatient Clinics in Germany: A Quality-of-Care Concern

Introduction: The aim of the study was to survey current practices for preventing recurrent stone disease in an outpatient clinic setting in Germany. Methods: Two invitations to complete an anonymous REDCap® survey were emailed to members of the occupational union of German urologists who work as outpatient urologists (“Berufsverband Deutscher Urologen e.V.”). The survey included questions on diagnostic modalities and counselling to prevent stone disease. Results: A total of 130 outpatient urologists completed the survey. 84.6% of urologists give general advice to first-time stone formers. Recommendations comprise increased fluid uptake in 100%, two-thirds advice on calcium and oxalate intake, and one-third on salt and protein intake. 64.6% perform a metabolic evaluation for high-risk stone formers. However, patients with risk factors other than repeat stone disease are often overlooked. Urologists agreed that a lack of time (73.1%) and reimbursement (64.6%), as well as insufficient patient compliance (60.8%), pose significant challenges. The majority of urologists agreed that training is required. Conclusion: General recommendations for stone formers are usually provided, but nutritional advice tends to be incomplete. Our results raise quality-of-care concerns: Metabolic evaluation of stone formers at high risk of recurrence is uncommon. Structural changes are required due to time constraints, and poor remuneration must be addressed to improve patient care.

Metabolic evaluation: is there really a future?

To confirm the need for a metabolic evaluation in stone formers based on the latest information published in the last 24 months and in the current 2022 American and European urological guidelines. Recent studies suggest that urolithiasis prevalence has been increasing since 1990. Along with it, metabolic abnormalities that contribute to the development of kidney stones are also increasing, such as hyperuricosuria, hyperoxaluria, hypocitraturia, hypomagnesuria, hypocalciuria, hypophosphaturia, and hyperuricemia. Those abnormalities can only be detected through a metabolic evaluation in patients with stone disease. It is important for us, urologists, to have in mind the actual stone prevalence worldwide. As part of our initial evaluation of the patient with urolithiasis, we must not forget to perform the basic metabolic analysis and, according to the patient's risk classification, continue with a deep metabolic analysis. This extensive analysis includes blood and urine tests. The urinalysis covers 24-h urinalysis, and it would be accurate to also have an early fresh urine analysis. Moreover, identifying the stone type is intimately correlated with the search for other metabolic parameters.

Acidification of 24-hour urine in urolithiasis risk testing: An obsolete relic?

BackgroundRecommendations on the optimal preservation of 24 h urine for the metabolic work-up in urolithiasis patients are very heterogeneous. In case two such tests with different storage condition recommendations are being analysed, multiple collections would be needed, challenging especially elderly and very young patients. We therefore aimed to evaluate the stability of urine constituents under different storage conditions. Material and methodsWe collected urine samples from ten healthy volunteers and prepared aliquots to be stored either at room temperature or 4 °C. Some aliquots were preserved using hydrochloric acid prior to storage, some thereafter, some using the BD Urine preservation tube and some were not preserved at all. Storage duration was 0, 24, 48 or 72 h. In all samples calcium, magnesium, phosphorus, creatinine, oxalate, citrate and uric acid were measured and compared to the according reference sample. ResultsWe could not find any significant deviation for any of the analytes and preanalytical treatment conditions compared to the associated reference sample. ConclusionPreservation of 24 h urine for the metabolic evaluation in stone formers might not be necessary for sample storage up to 72 h.

24-hour urinary constituents in stone formers: a study from Kashmir

Background: Urolithiasis is a common disorder. Studies have shown that metabolic causes of urolithiasis include hypercalciuria, hypocitraturia, high or low pH of urine, hyperuricosuria, hyperoxaluria and hypomagnesuria. We intended to conduct this study with the aim to provide historical data regarding the 24-hour urinary analysis in this part of India with a distinct and different geographical and cultural background.Methods: A total of 186 patients having urinary stone disease attending the departments of Nephrology and Urology in Sher-I- Kashmir institute of medical sciences were included. 26 healthy members of hospital staff were taken as controls. Demographic and clinico-pathological characteristics of each patient were recorded in a questionnaire. Urine was collected for 24-hours from 186 patients and 26 controls. 10ml sample of this urine collection was stored at 20c0 before processing for urinary parameters.Results: The mean concentration of calcium salts, Magnesium, Oxalate and Uric acid in the 24-hour urinary analysis of urolithiasis patients is higher than that of the normal healthy controls and the relation was statistically significant. On comparing the 24-hour urinary constituents among urolithiasis patients and health controls, the concentration of phosphate was almost equal in both cases and controls while the concentration of oxalate was much higher in cases than controls.Conclusions: In present study hypercalciuria is main cause of renal calculi along with hypocitraturia, hypomagnesuria and hyperphosphaturia in our valley. Measurement of 24-hour urine constituents is still gold standard for evaluation of stone formers.

Using 24-Hour Urinalysis to Predict Stone Type

We determined the accuracy of 24-hour urinalysis in predicting stone type and identify the associations between 24-hour urine elements with stone type. We performed a retrospective review of 503 stone formers with stone composition analysis and 24-hour urinalysis available. Analysis of 24-hour urine elements across stone types was performed using Fisher's exact test and ANOVA. Multinomial logistic regression was used to predict stone type based on 24-hour urinalysis. A total of 280 (56%) patients had predominantly calcium oxalate, 103(20%) had uric acid, 93 (19%) had calcium phosphate, 16 (3%) had mixed and 11(2%) had other stone types. There were several significant patient characteristics and 24-hour urinalysis differences across stone type groups. The statistical model predicted 371 (74%) calcium oxalate, 78 (16%) uric acid, 52 (10%) calcium phosphate, zero mixed and 2 (less than 1%) other stone types. The model correctly predicted calcium oxalate stones in 85%, uric acid in 51%, calcium phosphate in 31%, mixed in 0% and other stone types in 18% of the cases. Of the predicted stone types, correct predictions were 61%, 69%, 56% and 71% for calcium oxalate, uric acid, calcium phosphate and other stones types, respectively. The overall accuracy was 64%. Plots were used to explore the associations between each 24-hour urine element with each predicted stone type adjusted for all the others urinary elements. A 24-hour urinalysis alone does not accurately predict stone type. However, it may be used in conjunction with other variables to predict stone composition.

Demography and biochemistry of 2800 patients from a renal stones clinic

Because the causes of stones are uncertain, interventions to prevent recurrence have an insecure foundation. Progress depends on careful evaluation of stone formers. A descriptive retrospective database study of 1983 men and 816 women from the Southampton stones clinic from 1990 to March 2007. Anonymized data from the first attendance were analysed using non-parametric statistical tests. Sex ratio (2.43:1), age (median 49 y, 2.5th-97.5th percentiles, 23-77 y men, 20-79 y women), recurrent stone formers (30%) and type of stone were similar to other centres. Women more often had a positive family history (24% versus 19% men), previous urinary infection (31% versus 5%) and structural urinary tract abnormality (14% versus 7%); more men had gout (5% versus 1%) and bladder outlet obstruction (3% versus <1%). Calcium, oxalate and uric acid excretion were increased in 43%, 17% and 22% respectively of men and 31%, 7% and 10% of women. Urinary calcium, oxalate and uric acid correlated significantly, r ranging from 0.149 to 0.311 for 24 h excretion and 0.510 to 0.695 for concentrations per litre. Twenty-two percent of men and 8% of women with normal parathyroid hormone had phosphaturia (excretion of phosphate corrected for glomerular filtration rate (TmPO4/GFR) < 0.70 mmol/L); 6% men and 1.6% women also had low plasma phosphate. Many variables correlated significantly but often weakly with age. Creatinine clearance, pH and (men) TmPO4/GFR decreased from 50 y, urine creatinine, calcium and citrate from 60 y. Risk factors for stones differ between men and women, change with ageing and in some may have a genetic basis. The role of phosphaturia merits further exploration.

24-Hour Urine Collection in the Metabolic Evaluation of Stone Formers: Is One Study Adequate?

Abstract Purpose: To determine whether one vs two 24-hour urine collections is optimal in the metabolic evaluation of nephrolithiasis. We retrospectively reviewed all 24-hour urine collections performed at our tertiary stone clinic from July 1997 to February 2012. We identified patients with two 24-hour urine collections performed ≤10 days apart. Samples were analyzed by an outside laboratory for the standard urinary parameters. For each parameter, pairwise t tests were performed and Pearson correlation coefficients were calculated to compare samples 1 and 2. In addition, the number of cases that changed from normal to abnormal or vice versa was also evaluated for each parameter and the Kappa statistic was calculated. A total of 813 subjects submitted two 24-hour urine collections ≤10 days apart. Mean age was 53.2 years, and mean body mass index was 28.8 kg/m(2). Based on creatinine 24/kg, subset analysis was performed for all properly collected samples (n=236). Using pairwise t test, 24-hour urine volume (P=0.0365) and phosphorus (P=0.0387) showed a statistically significant difference between samples 1 and 2. None of the other urinary parameters demonstrated a statistically significant difference when means were compared (pairwise t test, P>0.05), (range 0.061-0.9983). Pearson correlation demonstrated a high degree of correlation between two 24-hour urines for all variables (r=0.66-0.95, each P<0.0001). Depending on the urinary parameter assessed, 5.5% to 44.9% of patients changed from normalcy to abnormality, or vice versa. A single 24-hour urine collection may have changed clinical decision making in up to 45% of patients. Therefore, we recommend two collections to optimize the diagnostic yield and appropriately target stone prevention strategies.

Urinary Metabolic Evaluation of Stone Formers—A Malaysian Perspective

To investigate the urinary metabolic excretion pattern among local stone formers given the great differences in the intrinsic and extrinsic risk factors as well as the urinary metabolic excretions compared with other populations. Thirty urinary stone formers out of an initial 62 recruited provided a complete 24-hour urine sample for metabolic evaluation. Student's t-test and Pearson correlation test were used for the statistical analysis. Urinary volume (1719 ± 712 vs 1215 ± 575, P < .05) and oxalate excretion (0.386 ± 0.111 vs 0.306 ± 0.104, P < .05) were significantly higher among stone formers than controls. Other commonly studied urinary parameters and urinary melamine did not differ significantly between the 2 groups. Similarly, the calcium/citrate ratio was unable to discriminate the stone formers from their controls. Hypocitraturia was the most prevalent urinary abnormality found in stone formers and low urinary citrate excretion was a general phenomenon in both stone formers and controls. Comparing within the stone formers cohort, the recurrent stone formers had a significantly higher urinary saturation and calcium excretion than their first-time stone former counterparts. Elevated urinary oxalate level was the most important urinary risk factor among the local stone formers. A low urinary citrate excretion appeared to be a general phenomenon among the studied cohorts.

Adequacy of a Single 24-Hour Urine Collection for Metabolic Evaluation of Recurrent Nephrolithiasis

There is much debate about whether 1 or 2, 24-hour urinalyses are adequate for metabolic evaluation of stone formers. We determined whether repeat 24-hour urine collection provides information similar to that of the initial 24-hour urine collection and whether repeat collection is necessary. We analyzed 2, 24-hour urine collections in 777 patients obtained from 2001 to 2005. Samples were collected 3 days or less apart before pharmacological intervention and analyzed elsewhere for routine stone risk profiles of urine calcium, oxalate, citrate, uric acid, sodium, potassium, magnesium, phosphorus, ammonium, chloride, urea nitrogen and creatinine. No parameters showed a statistically significant difference between 24-hour urine samples 1 and 2 when mean values were compared (pairwise t test each p >0.05, range 0.06 to 0.87). Using Pearson's correlation all parameters showed positive correlation coefficients (r = 0.68 to 0.89, each p <0.0001). The mean of individual patient differences in samples 1 and 2 were compared to 0 and 6 of 12 showed no difference (p >0.05) while for the remaining 6 p value was <0.05. The percent difference was 0.5% to 4.19% for all urinary parameters. One 24-hour urine sample is sufficient for metabolic evaluation of recurrent stone disease. There is no significant difference in 12 urinary parameters between 24-hour urine samples collected within 3 days of each other. This information is useful to providers and may decrease patient inconvenience and the overall cost of metabolic stone evaluation.

Medical evaluation and management of urolithiasis

Nephrolithiasis is a highly prevalent condition with a high recurrence rate that has a large impact on the quality of life of those affected. It also poses a great financial burden on society. There have been great advancements in the surgical treatment of stone disease over the past several decades. The evolution of surgical technique appears to have overshadowed the importance of prevention of stone disease despite evidence showing medical therapies significantly decreasing stone recurrence rates. Herein we review the metabolic evaluation of stone formers with the use of specific blood and urine tests. We complete our discussion with a review of the medical management of stone formers providing both general recommendations as well as reviewing focused therapies for specific metabolic abnormalities and medical conditions.

Twenty-four Hour and Spot Urine Metabolic Evaluations: Correlations Versus Agreements

To investigate the correlations and agreements between the solute/creatinine ratios from the 24-hour and early morning spot urine samples for metabolic evaluation in stone-formers given the various pitfalls with the 24-hour urinary metabolic evaluation in stone-formers. 30 urinary stone-formers out of an initial 62 recruited provided a complete 24-hour urine and early morning spot urine samples for metabolic evaluation. Pearson correlation and Bland and Altman Test were used to assess the correlations and agreements. Significant correlations were established between the 24-hour urinary solute excretions and the corresponding early morning spot urine solute/creatinine ratios for calcium, magnesium, urate, potassium, oxalate, citrate, and the Differential Gibb's free energy value of calcium oxalate DG(CaOx) values. However, all these solute/creatinine measurements between the 24-hour and early morning spot urine samples were judged to be not within the acceptable limits based on the estimated "limit of agreement" by the Bland and Altman Test of Agreement. Diurnal circadian rhythm and postprandial excretion surge are thought to be responsible for the disagreements. Thus, the early morning spot urine is not suitable to be used interchangeably to replace the 24-hour urine collection in the evaluation of urinary metabolic abnormalities in stone-formers. A good correlation does not translate to an agreement between the 2 measurements.

Serial crystalluria determination and the risk of recurrence in calcium stone formers

Urinary crystal precipitation is the necessary initial step in kidney stone formation. However, clinical relevance of crystalluria in the evaluation of stone formers is disputed. We serially determined crystalluria in first-voided morning urine samples, together with full 24-hour urine biochemistry, in 181 patients with idiopathic calcium nephrolithiasis who had formed at least one calcium-oxalate stone and were followed for at least 3 years under our care. All stone events which occurred prior to referral, then after entry in the study were recorded. As compared with 109 patients who had no evidence of stone recurrence during follow-up, the 72 patients who experienced >/= one recurrent stone event had a lower daily urine volume (1.74 +/- 0.06 vs. 2.26 +/- 0.05 L/day (mean +/- SEM) (P < 0.0001), higher urine calcium and oxalate concentrations, and daily calcium excretion, and they had more frequent crystalluria (68% vs. 23% of urine samples) (P < 0.0001). By multivariate Cox regression analysis, the hazard ratio for stone recurrence was 0.32 (95% CI 0.16-0.62) for 1 L increase in daily urine volume, 1.12 (1.09-1.24) for 1 mmol/L increase in urine calcium concentration, 1.24 (1.02-1.50) for 0.1 mmol/L increase in urine oxalate concentration and 27.8 (10.2-75.6) for crystalluria index. These data provide evidence that crystalluria, when repeatedly found in early morning urine samples, is highly predictive of the risk of stone recurrence in calcium stone formers. Serial search for crystalluria, a simple and cheap method, may be proposed as a useful tool for the monitoring of calcium stone formers, in addition to urine biochemistry.

Urolithiasis: Update on Metabolic Evaluation of Stone Formers

Metabolic abnormalities are identified in over 90% of stone formers and the institution of preventative dietary and medical measures has resulted in substantial reduction in stone recurrence rates. We review the contemporary approach to metabolic evaluation of urolithiasis.A careful medical and dietary history, stone analysis, serologic tests, and urinalysis constitute the initial screening regimen in patients who have been diagnosed with stones. Risk stratification of patients, based on the outcome of the initial screening tests, determines the need for and extent of urinary evaluation in individual stone formers. Conservative dietary measures or a simple metabolic evaluation and treatment has been described for first-time or low-risk stone formers, although the number of 24-h urine collections needed is debatable. A more extensive metabolic evaluation is recommended for recurrent or high-risk stone formers or for those in whom empiric treatment or medical therapy based on simplified evaluation is unsuccessful.Regardless of etiology, all stone formers should be counseled on dietary measures for stone prevention. The need for medication is determined by the results of 24-h urine analysis and the risk level of the patient. Cost effectiveness of the metabolic evaluation and treatment is strongly influenced by recurrence rate and efficacy of therapy.Metabolic evaluation and treatment has clearly been shown in randomized trials to reduce stone recurrence rates. Further study will determine the extent of evaluation necessary and the need for selective vs. empiric medical therapy for first-time and recurrent stone formers.

ESWL centers and determination of urinary calculus etiology. Results of a survey of 150 ESWL centers

Questionnaires were mailed anonymously to 150 German shock wave centers. Twenty questions addressed the following areas of interest: Facilities of the extracorporeal shock wave lithotripsy (ESWL) center (technical, personnel, laboratory, etc.) Cooperation at ESWL center with referring urologists Laboratory facilities versus actual metabolic work-up. The return rate was 114 of 150 (76%). Surprisingly, at 58% of the centers the average number of treatments is less than two per day. In 30% of the centers only chemical stone analysis is done! The final conclusion was that ESWL has largely replaced the causal metabolic work-up and subsequent metaphylaxis as a symptomatic measure against urolithiasis.

Spot Urine Samples for the Metabolic Evaluation of Urolithiasis Patients

This prospective study was initiated to assess the significance of spot urine specimens (SU) for the metabolic evaluation of stone formers. 68 stone patients (51 males, 17 females) and 20 controls (9 males, 11 females) participated. On 3 consecutive days, urine was collected. Fasting (SU1) and postprandial (SU2) SU were obtained. From these, aliquots were taken, all the other urine was mixed to obtain 24-hour timed specimens (24hU). In all specimens, pH, specific gravity, creatinine, calcium, magnesium, phosphate, citrate, uric and oxalic acids were measured. The latter analytes were related to creatinine (mmol/g creatinine). Pearson correlation coefficients with their levels of significance and the day-to-day variation were calculated. Using the values in the control group, normal values (means +/- 2 SD) were established. There was a significant correlation (p < 0.0001) between SU and 24hU for all parameters examined. The day-to-day variation of all analytes was considerable in SU and 24hU. Despite a minor inaccuracy by relating parameters to creatinine, SU are sufficient in the routine metabolic evaluation of stone formers, since a third of all 24hU has to be rejected because of considerable collection errors. SU circumvent this problem. Because of the day-to-day variation, 3 SU should be obtained to overcome the doubtful significance of one single specimen.