Which method is considered the best and most common for preserving urine samples?

Refrigeration of urine samples is considered the best and most common method for preservation because it effectively slows down bacterial growth and metabolic processes that can alter the composition of the urine. By cooling the sample, chemical changes and sedimentation can be minimized, ensuring the integrity of the specimen until analysis can be performed. This method is practical, easy to implement, and maintains the sample in a stable state without introducing foreign substances that could affect test results.

Other methods, while they have their uses, do not typically match the practicality and effectiveness of refrigeration. For example, adding preservatives may alter the sample’s chemistry or introduce variables that could affect the results. Using formaldehyde can be problematic due to its toxic nature, requiring careful handling and specific protocols, and may not be acceptable for all analyses. Acidification can also affect certain components of the urine, potentially compromising the reliability of some tests. Hence, refrigeration remains the preferred technique for urine sample preservation.