National League for Nursing (NLN PAX) Practice Exam

What change in kidney function occurs when a person becomes dehydrated?

1. The kidneys filter more water and there is less reabsorption of water from the blood.

2. The filtration rate of water remains constant and the reabsorption of water increases.

3. The filtration rate of water increases and the reabsorption of water remains constant.

4. No changes occur in kidney function.

The correct answer is: The filtration rate of water remains constant and the reabsorption of water increases.

When a person becomes dehydrated, the kidneys respond to conserve water and maintain homeostasis in the body. In this state, the filtration rate of water through the kidneys generally remains constant, but the kidneys increase the reabsorption of water back into the bloodstream. This adaptive response is primarily mediated by hormones such as antidiuretic hormone (ADH), which promotes reabsorption of water in the renal tubules, leading to a more concentrated urine output. Thus, the correct choice illustrates that as dehydration occurs, the kidneys work harder to retain water, contributing to an increase in water reabsorption while maintaining a relatively stable filtration rate.