What is a common non-blood specimen collected for testing?

Urine is a common non-blood specimen collected for testing for several reasons. It is easily obtainable and non-invasive, making it straightforward for both patients and healthcare providers. Urine tests are extensively used for various diagnostic purposes, including evaluating metabolic function, diagnosing infections, monitoring drug levels, and assessing kidney function. Urine can provide insights into a range of health issues due to the substances that are filtered out by the kidneys and excreted, offering a clear picture of hydration status and potential medical conditions.

While saliva, sputum, and hair are also valid specimens used in certain contexts, urine stands out due to its wide applicability in clinical practice and laboratory testing. Saliva can be used for hormone levels and some infectious diseases, sputum is mainly useful in respiratory conditions, and hair analysis can provide information about drug use and certain mineral levels, but these are more specialized compared to the broad use of urine in testing across numerous medical fields.