What does the kidneys do during dehydration?

During dehydration, the kidneys conserve water by concentrating urine and reducing its volume. They achieve this by reabsorbing more water back into the bloodstream, which is regulated by the hormone antidiuretic hormone (ADH). Additionally, the kidneys may also reduce sodium excretion to help retain more fluid in the body. This process helps maintain blood pressure and electrolyte balance during periods of low fluid intake.