Endourology and StonesCollection and Storage of Urine Specimens for Measurement of Urolithiasis Risk Factors
Section snippets
Urine Collection and Preservation
Spot urine samples from 21 healthy volunteers were collected in plastic bottles. Each fresh urine sample was divided into ten 10-mL aliquots: 2 without preservative, 2 with 0.01 g of thymol, 2 with 50 μL of 99% toluene, and 2 with 500 μL of 6 mol/L hydrochloric acid (HCl). The latter samples were not used for analysis of urate or measurement pH. To enable measurement of urate and pH, the remaining 2 samples were collected in bottles containing 500 μL of 0.3-mol/L sodium azide (NaN3).
All
Results
Table 2 shows the mean ± standard deviation of each urine constituent in samples from 21 volunteers, with different preservatives and under different storage conditions.
Comment
Principles for collection of 24-hour urine samples have been evaluated and discussed in previous studies3, 4, 5, 6 to establish the best technique for maintaining chemical stability during storage, transportation, and processing. The aim thereby simultaneously was to be both time saving and cost effective. As recommended, urine should be acidified with HCl for analysis of urine calcium, phosphate, magnesium, and oxalate. The role of acidification is to counteract the formation of poorly soluble
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2022, Clinica Chimica ActaCitation Excerpt :Therefore, 24 h urine samples may be collected without preservative and can be aliquot in the laboratory upon retrieval and acidified or alkalinized as required prior to analysis. Of note, the use of preservatives such as Thymol or Toluene have been proven useful to prevent bacterial growth [27]. There are some limitations to our study.
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2019, Journal of Pharmaceutical and Biomedical AnalysisCitation Excerpt :These differences were not observed after short-time storage at -20 °C. The reduction of the pH by the addition of HCl (200 μL of HCl 6 N per 10 mL of sample) into samples diminish CA degradation in line with previous results [34,35]. The effect of HCl has been reported to be related with avoiding CA hydrogenation [36].
Chinese expert consensus on metabolic evaluation and recurrence prevention of urolithiasis
2023, Chinese Journal of Urology
Financial Disclosure: The authors declare that they have no relevant financial interests.