Define "preanalytical variables" in the context of laboratory testing.

Preanalytical variables refer to factors that can influence the outcome of laboratory test results before any processing of the sample takes place. This phase encompasses a wide range of considerations including, but not limited to, the collection, handling, transportation, and storage of samples. These factors are crucial as they can significantly affect the integrity of the specimen and, consequently, the accuracy and reliability of the test results.

For instance, the time of day a sample is collected may impact certain test results due to biological rhythms, known as circadian rhythms. Additionally, the method of collection, such as whether a venipuncture is done correctly, can also introduce variability. Proper training and protocol adherence are necessary to minimize these preanalytical influences, ensuring that the results obtained reflect the true physiological state of the patient.

The other options explore areas that do not pertain directly to the preanalytical phase. Variables considered post-analysis relate to how results are interpreted after testing, while environmental testing is a specific category not synonymous with preanalytical variables.