Urine Collection Method Research Articles

Measuring Social Connectedness during Shared Leisure Activities Using Oxytocin: A Comparison of Sampling Urine versus Saliva

Leisure experiences are often associated with social connectedness. One measure of social connection underutilized in leisure studies is the neurohormone oxytocin. This methodological note considers issues researchers need to address when incorporating oxytocin in their study design. Noninvasive sources for sampling oxytocin include saliva and urine; however, the decision about which method to employ is not well documented. This study provides the first methodological note on collecting oxytocin in leisure studies and provides a comparison of urine vs. saliva measures for oxytocin in the context of leisure activities. Our findings indicate that urine samples are more sensitive to oxytocin change in leisure studies. The discussion provides additional practical implications for future research studies regarding the choice between urine and saliva data collection methods.

The Utility of Combined Urine Urea and Creatinine Clearance for Pretransplant Renal Function Assessment

Evaluation of donor renal function as glomerular filtration rate (GFR) is a crucial part of pretransplant workup. Most guidelines recommend measured GFR (mGFR) using exogenous markers with creatinine clearance (CrCl) as an alternative. However, exogenous markers are difficult to obtain and perform, and CrCl may overestimate GFR. We explore the use of CrCl and combined urea and creatinine clearance as an alternative for GFR assessment. A retrospective study involving 81 kidney donors from 2007 to 2020, with mGFR collected by chromium 51-labeled ethylenediaminetetraacetic acid (51Cr-EDTA) and CrCl and combined urea and creatinine clearance. We analyzed the performance of CrCl and combined urea and creatinine clearance against 51Cr-EDTA. Adequacy of urine volume was taken into consideration. A total of 81 candidates with a mean age of 44.80 ± 10.77 years were enrolled. Mean mGFR from 51Cr-EDTA was 123.66 ± 26.91 mL/min/1.73 m2, and combined urea and creatinine clearance and CrCl were 122.13 ± 47.07 and 133.40 ± 36.32 mL/min/1.73 m2, respectively. CrCl overestimated 51Cr-EDTA. Though combined urea and creatinine clearance had minimal bias, it had a lower correlation coefficient (0.25 vs 0.43), lower precision (49.51 vs 38.10), and slightly lower accuracy within 30% of 51Cr-EDTA (74.07% vs 76.54%). Combined urea and creatinine clearance did not improve the performance of CrCl. Nevertheless, it can potentially be used as first-line GFR assessment, followed by mGFR in selected donors, to ascertain threshold of safe kidney donation. A stringent urine collection method is essential to ensure accurate measurement.

The prevalence of empiric antibiotic use in an emergency department on children with suspected urinary tract infections: A retrospective study in Saudi Arabia

Objectives: The prescription of antibiotics for suspected urinary tract infection (UTI) is common practice and may result in unnecessary antibiotic exposure. Our goal was to review the diagnosis and management of UTI in an emergency department and to determine the goals of antimicrobial stewardship. Methods: This is a single-centre, retrospective study that was conducted among children aged between 12 months and 18 years old who had been discharged from the emergency department with a diagnosis of UTI in the period between January and August 2022. Clinical information, laboratory findings, urine collection methods and urine culture results as well as details of prescribed antibiotics were gathered. The relation between urinalysis characteristics and confirmed UTI was assessed as a secondary outcome of the study. Results: In this study, we were able to collect data for 183 children with a mean age of 4.2 (1.1-7.5) years and 82.5% of them were girls. Almost all children with UTI were discharged to home with prescribed antibiotics (98%) for a median duration of seven days ranging between 7-10 days. Among those who used antibiotics, 46.4% of the patients had negative urine cultures, resulting in 525 unnecessary antibiotic prescriptions. Presence of nitrite in the urine was the strongest and highly specific predictor of UTI (odds ratio of 20.22, P< 0.001). Conclusions: Current practice in the management of suspected pediatric urinary tract infections in the selected emergency department resulted in significant and unnecessary exposure to antibiotics. We set goals to reduce unnecessary antibiotic exposure, including improving the accuracy of UTI diagnosis, establishing a process to discontinue antibiotic consumption for negative cultures, and standardizing the duration of antimicrobials. Keywords: urinary tract infections, pediatrics, children, antimicrobial monitoring, urinalysis, antibiotics, empiric use, E. coli, nitrite, urine culture.

Quick-Wee method Versus Standard method for urine collection in infants 1-12 month old

BACKGROUND: Urinary Tract infections [UTI] often presents with fever and nonspecific findings in infants less than one year. So urine sample collection is mandatory for diagnosis or exclusion. Collecting Urine sample is very challenging in infants and choosing the method of collection must balance the reliability, speed and contamination. Clinical guidelines have different recommendations so there is a need for reliable collection method. Therefore this study was conducted to determine if a simple stimulation method (Quick–wee Method) increases the rate of clean catch voiding of urine within five minutes.
 METHODS: A prospective age and sex matched case control study in 1-12 months children conducted from June 2017 – June 2018 in Pediatric ward of Manipal college of medical sciences, Pokhara, after Ethical clearance from Institutional review Board [IRB]. The study population was randomized to either clean catch midstream urine with stimulation [Quick–Wee method] or without stimulation [Standard method]. The primary outcome was voiding of urine within 5 minute. Secondary outcome were waiting time for voiding, successful collection, parental satisfaction, and contamination. The analysis was done using SPSS version 20 and a ‘p’value <0.05 was considered statistically significant.
 RESULTS: Waiting time for voiding in Quick wee group was less and statistically significant compared to standard group. There was 10% increment in voiding within 5 minutes in Quick wee group . It had higher successful urine collection rate (91.4%), slightly higher contamination rate (14.28%) but better parental satisfaction.
 CONCLUSIONS: Quick wee method is easy, reliable, successful method of urine collection in infants with better parental satisfaction and slightly higher contamination rate.

PSI-2 A procedure for urine collection in pre-weaned heifer calves

Abstract Urine collection is a useful tool to analyze intestinal permeability in cattle for research and diagnostic purposes. However, urine sampling techniques often rely on total waste collection, which reduces the ability to perform more frequent sampling and obtain accurate and sterile urine volumes. A potential alternative is urethral catheters, which have been used in cows and weaned heifers. However, urethral catheters have not been thoroughly tested in pre-weaned dairy heifer calves. The study objective was to develop a urethral catheter placement procedure in pre-weaned heifer calves for continuous and accurate urine collection. Fifteen Holstein heifer calves had catheters placed at 8 ± 2 days (37.5 ± 3.38 kg BW) and 40 ± 2 days (59.3 ± 5.38 kg BW) of age. During the procedure, calves were individually housed (1.87 m2/calf) and restrained. The vulva was cleaned using betadine and 70% ethanol and then a sterile, lubricated 8.9 cm speculum was inserted into the vagina. A sterile guidewire (145 cm x 0.89 cm) was inserted into a lubricated sterile 10 FR catheter. The catheter was inserted into the urethral opening (~5–7 cm into vagina), guided into the bladder, and the catheter balloon was filled with water (10 mL). The guide wire was removed, and urine flow confirmed correct placement before a 4 L urinary drainage bag was attached to the catheter. Individual calf health observations were made twice over a 24-hour period and included vaginal discharge, bleeding, redness or inflammation, and tissue discharge in the urine. Occurrence rate was determined using PROC FREQ in SAS 9.4. Regardless of catheterization timing, bleeding and tissue discharge occurred at a rate of 3.33% ± 0.18, and vaginal discharge and inflammation occurred at a rate of 6.70% ± 0.25. In summary, this procedure is a viable method for total urine collection in pre-weaning heifer calves.

Urinary Bladder Microbiome Identification Protocol with Proteomics in Bladder Cancer Patients and Review of the Literature

Abstract Urine was conventionally thought to be sterile. However, recent evidence about the presence of microorganisms residing the urinary tract has led to an emerging field of investigation about the potential role of urinary microbiome in the pathogenesis of urinary bladder cancer. Urinary microbiota refers to the different microbe populations present in the urinary tract while a variety of genetic, environmental, and experimental parameters have been investigated as predisposing factors of microbial composition. Different methods of urine collection as well as experimental methodology on microbiome’s characterization consist of well-defined factors that may alter the microbial composition. Few preliminary data have been reported so far implicating microorganisms as causative and prognostic factors of bladder tumorigenesis, examining mostly midstream-voided urine samples while the most commonly used analyzing technique was 16S rRNA sequencing method. In the present study, a protocol of microbiome identification using proteomics is reported analyzing differences in microbial composition between bladder cancer patients and healthy controls while a review of the current evidence is presented. To the best of our knowledge, proteomics has not been described as a possible method of microbiome characterization before.

Effects of dietary supplementation with alpha-lipoic acid on apparent digestibility and serum metabolome alterations of sheep in summer.

To investigate the effects of alpha-lipoic acid (LA) on the nutrition metabolism of sheep (36.72 ± 1.44kg) in the summer, twenty-one sheep were randomly assigned to three treatments addressing LA supplementation: 0.00 (CTL), 600 (LA-L), and 900 (LA-H) mg/kg of dry matter (DM) per day for each sheep. Whole feces and urine collection methods were used to analyze apparent digestibility; ELISA kits to determine the hormones, antioxidant, and immune parameters in the blood; and serum metabolomics to detect and analyze small molecular substances. The results showed the DM intakes in the LA-L and LA-H groups were significantly increased by 8.22% and 8.02%, respectively, compared to that in the CTL group, and there was no significant effect on average daily gain, feed conversion ratio, nitrogen digestibility, calcium digestibility, and phosphorus digestibility. Regarding hormones, antioxidant, and immune indicators, the concentrations of triiodothyronine, superoxide dismutase, glutathione reductase, HSP70, and IgA significantly increased after LA supplementation, while adrenaline and malondialdehyde levels significantly decreased. With the pairwise comparison of the three groups, metabolomics analysis identified 22 differential metabolites in the positive/negative modes, respectively, which suggested LA supplementation can significantly affect sheep's lipid, amino acid, and nucleic acid metabolism. Additionally, 3-indolepropionic acid, cinnamoylglycine, butyric acid, dodecanedioic acid, indoxyl sulfate, and pantothenic acid were the common differential metabolites with higher concentrations after LA supplementation. In summary, dietary supplementation of LA can increase the sheep's DMI, energy digestibility, antioxidant capacity, and immunity. These changes provide evidence to support the use of LA supplementation for livestock.

Non-invasive urine collection-floor pit method in captive sloth bears (<em>Melursus ursinus</em>)

Urine plays an important role in understanding metabolic conditions, reproductive status and stress physiology. We report here an effective non-invasive method of urine collection from captive Sloth bears (Melursus ursinus). The role of hormonal profiling and urinalysis are described. The pertinency of this method and its purpose for conservation are discussed.

Outpatient urine collection methods for paediatric urinary tract infections: Systematic review of diagnostic accuracy studies.

To investigate the diagnostic test accuracy of urine collection methods for urinary tract infections in outpatient children. A systematic literature review until April 2021 (Medline, Web of Science, Embase, Cinahl) to examine the diagnostic test accuracy of urine culture on collection methods for urinary tract infection in outpatient children below 18years. Contamination rates were studied as secondary outcome. The risk of bias was assessed using the QUADAS-2 criteria. Two-by-two tables were extracted in duplicate to calculate sensitivities, specificities, and likelihood ratios with 95% confidence intervals. The search identified seven relevant studies. Clean catch compared to catheterization in children less than 90days showed a sensitivity and specificity of 97% and 89% (95% CI: 84%-100% and 67%-99%), respectively. Adhesive bags compared to catheterization showed a sensitivity of 83% (95% CI: 75%-90%) and specificity of 91% (95% CI: 83%-96%). There was a similar diagnostic accuracy when comparing urine sampling by means of adhesive bags versus nappy pads. The contamination rate was 5% for clean catch, 30%-80% for adhesive bags and 64% for nappy pads. Nappy pads and adhesive bags are easy to use with comparable accuracy but are extremely prone to contamination. Clean-catch urine sampling might be an accurate alternative in young infants in ambulatory care.

Urine collection methods for infants under 3 months of age in clinical practice

Methods of urine collection used in precontinent children are a controversial issue. Definitive diagnosis of urinary tract infection (UTI) requires an uncontaminated urine culture. We aimed to describe methods used to collect urine for culture in infants under 3 months of age and compare results and contamination rates. This retrospective observational cohort study included 721 urine cultures collected from infants <3 months of age at the Hospital Universitario Infanta Sofía, Madrid, between January 2016 and December 2019. Urine cultures were compared based on collection technique, sex, and patient age. Median patient age was 36 days and 54.6% were male. In total, 592 (82.1%) samples were collected using clean-catch urine stimulation technique (CCUST), 77 (10.7%) by urethral catheterization (UC) and 52 (7.2%) by urine bag (UB). Positive cultures were obtained in 11.7% (95% confidence interval [CI] 9.1, 14.3) of CCUST samples and in 28.6% (95% CI 18.5, 38.7) of UC samples (p<0.001). The contamination rate was 13.7% (95% CI 10.9, 16.4] for CCUST, 23.1% (95% CI 11.6, 34.6) for UB and 5.2% (95% CI 0.2, 10.2) for UC, with statistically significant differences (p=0.007) between UB and UC collection. CCUST is the most commonly used method in our hospital for collecting urine in infants younger than 3 months. The contamination rate of UC is lower but not significantly different to that of CCUST. Urine collection by CCUST serves as a non-invasive alternative to UC for diagnosis of UTI in infants under 3 months of age in routine clinical practice. Graphical abstract.

WITHDRAWN: The Potential of Spot and Overnight Urine in the Evaluating of Proteinuria and Electrolyte

Abstract Urine testing has been a primary standard clinical method for assessing proteinuria and electrolyte intake. The traditional 24 ​h urine collection method, despite its high accuracy, has some limitations in practice. To overcome its drawbacks, two alternatives are widely recommended: spot urine collection and overnight urine collection. However, questions about the ability of the two alternatives in replacing the 24 ​h urine collection are still on debate, which requires further investigation. This article makes a systematic review of the two alternatives methods for assessing proteinuria and electrolyte, which may provide a useful insight for using them in actual clinical evaluation and diagnosis.

Comparison of two human infant urine collection methods for measuring estrone‐3‐glucuronide

Current human infant urine collection methods for the field are problematic for the researcher and potentially uncomfortable for the infant. In this study, we compared two minimally invasive methods for collecting infant urine: organic cotton balls and filter paper. We first collected urine from infants using the clean catch method. We then used those samples to compare the performance of filter paper and cotton ball collection protocols. We analyzed the clean catch and cotton samples using commercial estrone-3-glucuronide (E1G) kits and tried two different extraction methods for the filter paper. Using a paired t-test (n=10), we compared clean catch and cotton samples. We also compared effect sizes within and between methods. We were unable to extract enough urine from the filter paper to successfully assay the samples for E1G. The paired t-test revealed a statistically significant difference between the clean catch and cotton methods (t=2.63, p-value=0.03). However, the effect size was small (5.91 μg/ml, n=10, 95% CI=3.80, 8.02) and similar to or larger than the difference seen between duplicate wells for clean catch and cotton values. While this study is limited by sample size, our results indicate that filter paper is not a field-friendly method for collecting infant urine. However, we found that organic cotton balls showed similar values to the clean catch method, and we propose this method as an alternative, minimally invasive method for study of E1G in human infant urine.

Magnitude of post-urethroplasty urinary tract infections in children with hypospadias at a tertiary hospital in Kenya

Children who have undergone urethroplasty procedure for hypospadias are at a higher risk of getting urinary tract infections (UTI). This may be due to urethral scarring following urethroplasty that acts as a nidus for UTI. The risk is also attributed to urine stasis due to complications of urethroplasty such as urethral diverticulum, urethral stricture, meatal stenosis or breakdown of urethroplasty. Hypospadias is associated with mullerian duct remnants such as mullerian duct cysts and enlarged prostatic duct utricle which may lead to recurrent UTI. To determine the magnitude of urinary tract infections after urethroplasty for hypospadias in children at Kenyatta National Hospital (KNH), a tertiary hospital in Kenya. This was a prospective descriptive cross-sectional study of male children with hypospadias who had undergone urethroplasty between January 2014 to December 2018 (5years) at KNH with age range from 6 months to 18 years. Appropriate urine collection method was used to obtain the urine specimen for microscopy, culture and sensitivity tests. Data collected was analyzed using STATA 15. Significance of the results was considered at 95% confidence interval. The total number of patients seen and urine samples collected was 83 boys. The prevalence of UTI following urethroplasty for children with hypospadias was 6% (5/83). They all had UTI symptoms. Of the patients who had UTI, 60% was due to Enterobacter coli, 20% Pseudomonas aeruginosa and 20% Enterobacter cloaca complex. E.coli was 100% sensitive to nitrofurantoin, amoxicillin/clavulanic acid and cefazolin while 33% resistant to ciprofloxacin and Trimethoprim/sulfamethoxazole. Majority of the patients with UTI (80%) had penoscrotal hypospadias and 60% of them developed complications post-operatively. Urinary tract infections is not a common finding in children who have undergone urethroplasty for hypospadias at KNH. Patients with penoscrotal hypospadias appears to be at a higher risk of developing UTI in our institution with E. Coli being the commonest bacteria implicated. Antibiotic protocol should be based on local culture and sensitivity pattern.

Urinary microbiota of women with recurrent urinary tract infection: collection and culture methods.

Many clinicians utilize standard culture of voided urine to guide treatment for women with recurrent urinary tract infections (RUTI). However, despite antibiotic treatment, symptoms may persist and events frequently recur. The cyclic nature and ineffective treatment of RUTI suggest that underlying uropathogens pass undetected because of the preferential growth of Escherichia coli. Expanded quantitative urine culture (EQUC) detects more clinically relevant microbes. The objective of this study was to assess how urine collection and culture methods influence microbial detection in RUTI patients. This cross-sectional study enrolled symptomatic adult women with an established RUTI diagnosis. Participants contributed both midstream voided and catheterized urine specimens for culture via both standard urine culture (SUC) and EQUC. Presence and abundance of microbiota were compared between culture and collection methods. Forty-three symptomatic women participants (mean age 67years) contributed specimens. Compared to SUC, EQUC detected more unique bacterial species and consistently detected more uropathogens from catheterized and voided urine specimens. For both collection methods, the most commonly detected uropathogens by EQUC were E. coli (catheterized: n = 8, voided: n = 12) and E. faecalis (catheterized: n = 7, voided: n = 17). Compared to catheterized urine samples assessed by EQUC, SUC often missed uropathogens, and culture of voided urines by either method yielded high false-positive rates. In women with symptomatic RUTI, SUC and assessment of voided urines have clinically relevant limitations in uropathogen detection. These results suggest that, in this population, catheterized specimens analyzed via EQUC provide clinically relevant information for appropriate diagnosis.

Urinary microbiota; Which non-ınvasive urine collection method should we use?

The aim of this study is to establish the optimal non-invasive urine sample collection method for the microbiota studies. Twelve men with bladder carcinoma underwent first voided and midstream urine collection. Urine samples were analysed using V3-V4 regions of bacterial 16s ribosomal RNAs. Bacterial groups with relative abundance above 1% were analysed in first voided urine and midstream urine samples at phylum, class, order and family level. At the genus level, all of the identified bacterial groups' relative abundances were analysed. The statistical significance (P<.05) of differences between first voided and midstream urine sample microbiota was evaluated using the Wilcoxon test. According to the analysis, 8 phyla, 14 class, 23 orders, 39 families and 29 different genera were identified in the first voided and the midstream urine samples. Statistical differences were not identified between first voided and midstream urine samples of all bacteria groups except the Clostridiales at order level (p:0.04) and Clostridia at class level (P: .04). Either first voided or midstream urine samples can be used in urinary microbiota studies as we determined that there is no statistically significant difference between them regarding the results of 16s ribosomal RNA analysis.

Contamination rates of different methods of urine culture collection in children: A retrospective cohort study.

Urinary tract infection is a common cause of paediatric morbidity. However, there is no consensus on the default method for urine culture collection in children. This study aimed to examine the contamination rates of different urine collection methods. This was a retrospective cohort study in a paediatric emergency department. Data were collected from electronic health records on all children whose urine culture samples were obtained in the paediatric emergency department between March 2018 and March 2019. Different methods of urine collection included the midstream (MS) method, clean catch (CC), transurethral bladder catheterisation and suprapubic aspiration. Contamination rates and positive urine culture rates were calculated and compared for sex, age, and collection method. Urine culture samples were collected from 1507 children. There were 284 (18.8%) cultures that were positive with significant growth and 52 (3.5%) that were defined as 'contaminated'. The contamination rates for the midstream method in toilet-trained children were 1.6% (10/609), 4.9% (17/348) for CC in pre-continent children, 4.9% (25/515) for transurethral bladder catheterisation and 0% (0/35) (P=0.006) for suprapubic aspiration. There was no significant difference in contamination rates of urine cultures collected by CC and catheterisation in the compared groups. The rates of positive cultures in the subgroup of children with high suspicion for Urinary tract infection were also found to be similar. Our study shows that CC is non-inferior to catheterisation for collecting urine cultures in young children.

Reliability of a dried urine test for comprehensive assessment of urine hormones and metabolites

BackgroundMass spectrometry allows for analysis of multiple hormone and organic acid metabolites from small urine volumes; however, to assess the full extent of daily hormone production, 24-h urine collections are usually required. The aims of this study were, first, to confirm that mass spectrometric analysis of an array of hormones and organic acids would yield similar results in both liquid and dried urine, and, second, to determine if collection of four dried spot urine samples could be substituted for a 24-h collection when measuring reproductive hormones.MethodsTwo study populations were included in this prospective observational study. Twenty individuals collected both a spot liquid urine and dried urine on filter paper to analyze eight organic acids. A second group of 26 individuals collected both a 24-h urine and four dried spot urines during waking hours throughout the same day for evaluation of 17 reproductive hormones and metabolites; data from 18 of these individuals were available to compare liquid versus dried urine results. Dried urine was extracted, hydrolyzed, and derivatized before analysis by mass spectrometry; all analytes from dried urine were normalized to urine creatinine.ResultsReproductive hormone results from dried and liquid urine were in excellent agreement with intraclass correlation coefficients (ICCs) greater than 0.90; comparison of dried to liquid urine for organic acids showed good to excellent agreement (ICC range: 0.75 to 0.99). Comparison between the 4-spot urine collection and 24-h urine collection methods showed excellent agreement (ICC > 0.9) for 14 of the 17 urine metabolites and good agreement for the others (ICC 0.78 to 0.85) with no systematic differences between the two methods of collection.ConclusionsThe burden of urine collection can be reduced using collection of four spot dried urines on filter paper without compromising comparability with hormone results from a 24-h urine collection. A large number of urine analytes can be assessed from the dried urine with similar results to those from liquid urine. Given the ease of sample handling, this 4-spot dried urine assay would be useful for both clinical assessment of patients and for large epidemiologic studies.

Baseline urinalysis results in 32 healthy Antillean manatees (Trichechus manatus manatus).

To describe results of analysis of free-catch urine samples collected from Antillean manatees (Trichechus manatus manatus) under human care in the Caribbean. 32 Antillean manatees in 5 Caribbean oceanaria and rescue centers. Urine samples were obtained by opportunistic free catch during physical examination or through the use of operant conditioning procedures. Urinalyses consisted of macro- and microscopic evaluations, biochemical analyses with test strips, and refractometry. Results were compared for manatees grouped on the basis of age, sex, and habitat. Urine samples were typically clear, straw colored, and alkaline (mean pH, 8.0); had a urinoid odor and low specific gravity (mean, 1.010); and had results on qualitative test strips that were consistently negative for the presence of glucose, bilirubin, ketones, proteins, nitrites, RBCs, and WBCs. Microscopically, the mean ± SD number of RBCs and WBCs/hpf was 0.5 ± 0.3 RBCs/hpf and 1.1 ± 1.5 WBCs/hpf. The presence of some epithelial cells and crystals was typical. Spermatozoa were found in urine from 1 of 15 sexually mature males, and parasite larvae and eggs were found in urine from 2 manatees. Results of the present study yielded the first compilation of baseline urinalysis values in healthy Antillean manatees under human care, which, when combined with physical examination and other diagnostic procedures, can help in monitoring the health of these animals. We encourage the use of free-catch urine collection methods, as used in the present study, for routine urinalyses of manatees under human care in zoos, aquaria, or rescue centers.

Are individual analyses of multiple short urine collections throughout the 24 hours superior to a standard 24‐hour urine collection in precipitation risk assessment of healthy subjects?

The commonly used 24-hour collection technique has been the mainstay of diagnosis for supersaturation but has some certain limitations. Hence, superiority of multiple short urine collections as a new alternative in precipitation risk assessment was assessed compared to the standard 24-hour urine collection among healthy subjects. Individual urine samples of 26 healthy subjects were acquired every 2 to 3 hours throughout the 24 hours. Urine samples were obtained and the time and volume of each sample were recorded. Urinary constituents involved in precipitation including, sodium-potassium, chloride, calcium, phosphate, citrate, magnesium, urea, creatinine and pH were measured. A simulated 24-hour collection was recalculated by the totalling of all shorter urine collections volume and urinary constituents excretions throughout the day. Urine pH, urine creatinine and precipitation rate had a significantly lower values in 24-hours urine collection compared to one individual value of multiple urine collections by -0.769 (P < .0001), -7.305 (P < .0001), and - 12.838 (P < .0001), respectively. However, calcium (2.697, P < .0001), citrate (3.54, P < .0001), total phosphate (19.961, P < .0001) and total creatinine (9.579, P < .0001) had statistically significantly higher values in the 24-hours urine collection compared to individual value of multiple urine collections. Based on the results, individual analysis of multiple shorter urine collections throughout the day improves the ability of identifying supersaturation points, precipitation risk zones and may potentially improve risk assessment compared to the 24-hour urine collection method.

The potential of spot and overnight urine in the evaluating of proteinuria and electrolyte

Urine testing has been a primary standard clinical method for assessing proteinuria and electrolyte intake. The traditional 24 ​h urine collection method, despite its high accuracy, has some limitations in practice. To overcome its drawbacks, two alternatives are widely recommended: spot urine collection and overnight urine collection. However, questions about the ability of the two alternatives in replacing the 24 ​h urine collection are still on debate, which requires further investigation. This article makes a systematic review of the two alternatives methods for assessing proteinuria and electrolyte, which may provide a useful insight for using them in actual clinical evaluation and diagnosis.