Why is it recommended to protect a urine specimen from light?

Protecting a urine specimen from light is essential primarily to prevent the degradation of the sample. Certain substances found in urine, such as bilirubin and various vitamins, are sensitive to light and can break down when exposed to it. This degradation can lead to inaccurate laboratory results, particularly affecting tests that rely on the quantification of these components.

For instance, bilirubin is a pigment that, if broken down due to light exposure, can lead to falsely low measurements, which could interfere with diagnostic accuracy. Ensuring that the specimen is shielded from light—by using opaque containers or aluminum foil—preserves its integrity and helps in obtaining reliable results from subsequent analyses.

The other choices are important considerations in specimen collection and processing but do not directly relate to the need for light protection. Maintaining pH is influenced by various factors and requires specific storage conditions, while enhancing bacterial growth and avoiding contamination pertain to handling and storage practices but do not specifically involve the light sensitivity of urine components.