Final answer:
A urine specimen left out can experience bacterial growth, a change in pH (initial increase due to urea breakdown and possible subsequent decrease), an increase in specific gravity due to water evaporation, and decreased glucose levels from bacterial metabolism.
Step-by-step explanation:
When a urine specimen remains on the counter for an extended period, several changes can occur:
- Bacterial growth may take place since urine that is left unrefrigerated can become a breeding ground for bacteria, leading to an increase in bacterial count.
- The pH of the specimen may initially increase due to the breakdown of urea to ammonia by urease-producing bacteria, making the urine more alkaline. Eventually, as other metabolic processes take place, the pH may decrease.
- If water evaporates from the specimen, this could lead to an increase in specific gravity as the concentration of solutes becomes higher.
- Decreased glucose levels could occur as bacteria utilize glucose for their metabolism.
In addition to these changes, the specimen's color, odor, and composition can also alter over time. For example, the presence of white blood cells in urine often suggests a urinary tract infection (UTI). In the context of specific gravity, conditions like diabetes insipidus would cause a decrease, whereas dehydration might lead to an increase.