In a healthy person, which substance is NOT removed via the kidneys?

In a healthy individual, glucose is typically not removed by the kidneys under normal circumstances because it is a crucial source of energy for the body. The kidneys filter blood, and while they do process glucose, they usually reabsorb it back into the bloodstream almost entirely when functioning properly. This reabsorption occurs in the proximal convoluted tubule of the nephron, where specialized transport mechanisms ensure that glucose is retained.

In contrast, substances like urea and creatinine are waste products that are filtered out of the blood and excreted in urine. Sodium is also regulated by the kidneys, but in the case of excess sodium in the body, it is removed through urine. The kidneys play a vital role in maintaining homeostasis in the body by adjusting the levels of these substances based on metabolic needs. Therefore, the reason glucose is not removed in significant amounts is due to its essential role as an energy substrate, making it the correct answer to this question.