Which of the following is NOT a disorder of the excretory system?

Liver failure is not classified as a disorder of the excretory system because the excretory system primarily includes organs responsible for the elimination of waste from the body, such as the kidneys, ureters, bladder, and urethra. The liver, while vital for many metabolic processes and detoxification, is part of the digestive system rather than the excretory system. It plays a key role in processing nutrients and producing bile, but it does not directly participate in the elimination of waste products like the organs of the excretory system do.

In contrast, conditions like kidney stones, urinary tract infections, and renal insufficiency directly impact the functions and health of the kidneys and urinary tract, which are integral components of the excretory system.