Which of the following substances is not usually present in the urine of a healthy person?

Glucose is not usually present in the urine of a healthy person. Glucose is a type of sugar that is normally present in the blood, but it is typically filtered out by the kidneys and reabsorbed back into the bloodstream. If there is too much glucose in the blood, such as in the case of diabetes, the kidneys may not be able to reabsorb all of it and some may end up in the urine. This is why glucose is sometimes present in the urine of people with diabetes, but it is not typically present in the urine of healthy individuals. On the other hand, urea, mineral salts, and water are all normally present in the urine of healthy people. Urea is a waste product that is produced when the body breaks down protein, and it is filtered out of the blood by the kidneys and excreted in the urine. Mineral salts such as sodium, potassium, and calcium are also filtered out of the blood by the kidneys and excreted in the urine, along with excess water.