Which method is most commonly used for the preservation of urine samples?

The preservation of urine samples is crucial in maintaining the integrity of the specimen for accurate laboratory analysis. Refrigeration at 2-8°C is the most commonly used method because it effectively slows down bacterial growth and chemical changes that can affect the composition of the sample.

Keeping urine samples at refrigerator temperatures minimizes the risk of decomposition and ensures that the analytes (such as glucose, protein, or cellular components) remain stable until analysis can be performed. This temperature range is deemed optimal for short-term storage, allowing the samples to be preserved without causing precipitation or alteration of the urine components.

Other methods, such as freezing at -20°C, while effective in certain situations, can lead to cellular lysis and changes in composition that may not reflect the original sample upon thawing. Evaporation at room temperature is not a reliable method as it would likely lead to significant loss of volatiles and alteration in concentration. Alcohol preservation is typically not used for urine samples since it can interfere with many of the tests performed on the samples.

Thus, refrigeration at 2-8°C stands out as the standard practice for preserving urine samples in a clinical laboratory setting.