Which of the following factors can lead to a false positive on urine glucose tests?

A false positive result in urine glucose tests can occur due to high levels of certain substances in the urine that interfere with the test's chemical reaction. Excessive vitamin C intake can lead to this situation. Vitamin C, or ascorbic acid, has the potential to interfere with the glucose oxidase method commonly used in urine tests. This interference can result in a falsely elevated glucose level in the testing.

In contrast, while factors like a high protein diet, dehydration, or the presence of ketones might affect urine composition or concentration, they are not known to directly cause a false positive on standard urine glucose tests. Understanding this specificity is crucial for accurately interpreting test results in clinical settings.