In addition to the time of sampling, the duration until the analysis of the urine sample also plays a quite relevant role.
Duration of analysis
All information on the topic of analysis duration
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There are not many studies on this subject yet, but the statements of the acquaintances are noteworthy.
Thus, Dolscheidt et. Al note that most parameters depend crucially on the time window between sampling and analysis. The study emphasizes the importance of adherence to early measurement times in urinalysis (within 90 minutes). Especially with parameters for the determination of urinary tract infections and proteinuria. One limitation of the study is the fact that the study used an older device model, but it is still widely used.
Veljkovic et al. found in a multicentre study that the urine can be stored at room temperature for up to four hours without significant changes in urinalysis. However, the urine must be treated appropriately (e.g. immediate cooling), otherwise further errors could occur. In principle, many laboratories reject the study if the time window between sampling, transport and arrival in the laboratory exceeds four hours.
Basically, there is a limitation through the time window, which can be different length depending on the measurement method.
The topic of proper treatment of urine after sampling (cooling) is also included in a comprehensive study by Bekeris. et al. Found. The collection location had no influence on the contamination rate, but the subsequent processing, in particular cooling of the sample, had a significant impact. Providing instructions to patients resulted in a statistically significant reduction in contamination rates for samples, especially in male patients.
In summary, it can be said that urine can certainly bridge some time until analysis if stored properly (immediate cooling). However, in case of improper>storage and longer duration (90min) up to the analysis – especially in summer – measurement results are quite critical to question.
- Dolscheid-Pommerich, R. C: et al. (2016): “Evaluation of the appropriate time period between sampling and analyzing for automated urinalysis”, Medica, 82-89
- Veljkovic, K. et al. (2012): “Assessment of a four hour delay for urine samples stored without preservatives at room temperature for urinalysis”, Biochem., Vol. 45, No10-11, 856-858
- Bekeris et al. (2008): “Urine Culture Contamination”, Arch Pathol Lab Med—Vol. 132