What characteristic of urine supports its use in clinical laboratories?

The characteristic that supports the use of urine in clinical laboratories is its ease of collection and analysis. Urine can be obtained non-invasively from patients, making it a practical choice for routine assessments and diagnostic testing. This simplicity in collection allows for rapid and convenient sampling, which is vital in clinical settings where timely results are needed for diagnosis and treatment. Additionally, the ability to analyze urine for various substances offers valuable insights into a patient's health status, especially concerning metabolic, kidney, and systemic conditions.

Other characteristics may not have the same clinical utility. High viscosity is not a typical feature of urine and does not contribute to its diagnostic capabilities. A highly variable composition could complicate results, leading to challenges in interpretation. Lastly, while urine can be produced in abnormal amounts in certain medical conditions, this variability does not inherently support its use in the laboratory; in fact, it may complicate the clinical picture rather than clarify it. Thus, the ease of collection and subsequent analysis is the most relevant attribute that makes urine a staple in clinical laboratories.