What effect does concentrated urine have on red blood cells?

Concentrated urine can lead to an increase in osmolarity, which may cause red blood cells to lose water and shrink, a process known as crenation. This hyperosmotic environment can disrupt the normal function of red blood cells, impairing their ability to transport oxygen effectively. Additionally, if the concentration of certain solutes becomes excessively high, it may lead to potential toxicity or hemolysis, where the red blood cells break down. Overall, concentrated urine can adversely affect the integrity and functionality of red blood cells.