What type of specimen is collected over a predetermined time period to obtain specific information?

A timed specimen is collected over a specific period to measure the concentration and quantity of substances within that timeframe. This method is often employed in various diagnostic tests to assess levels of chemicals, hormones, or other substances that may fluctuate throughout the day due to metabolic or physiological processes.

For example, a 24-hour urine collection is a common practice in timed specimen collection, allowing healthcare professionals to evaluate kidney function, hormone levels, or the presence of certain metabolites more accurately. Collecting the specimen over a specific time period helps ensure that factors like diurnal variation and random fluctuations do not obscure the test results, providing more reliable and meaningful information for diagnosis or monitoring.

In contrast, random specimens do not have a specific collection time and may not accurately reflect fluctuations in certain analytes. First-voided morning specimens are particularly useful for specific tests such as pregnancy tests or tests requiring concentrated urine, but they are not collected over a stipulated time like timed specimens. Spot specimens refer to samples collected without a designated timeframe and do not provide the same consistent and comprehensive data that timed specimens offer.