What is the use of ADH what does it do?

When blood is too concentrated, more ADH released by pituatary gland and causes kidney tubles to be more permeable allowing more water to be absorbed into the blood during selective reabsorbtion more water lost as urine When blood is too dilute, less ADH released by pituatary gland and causes kidney tubles to be less permeable allowing less water to be absorbed into the blood during selective reabsorbtion less water lost as urine