Which substance is NOT normally found in urine?

The substance that is not normally found in urine is glucose. Under typical circumstances, kidneys effectively filter blood and reabsorb glucose back into the bloodstream. Therefore, glucose should not be present in urine at significant levels in healthy individuals.

When glucose appears in the urine, it often indicates that blood glucose levels are above the renal threshold for glucose reabsorption. This can occur in conditions such as uncontrolled diabetes mellitus, which can lead to glucosuria, or glucose in the urine.

The other substances listed—urea, creatinine, and uric acid—are routinely found in urine. Urea is a waste product generated from protein metabolism, creatinine is a breakdown product of muscle metabolism, and uric acid is produced from the breakdown of purines. All of these substances are normally excreted by the kidneys as part of the body’s waste management system.