Antidiuretic hormones are peptides that are produced in the hypothalamus and are released by the pituitary glands. Diuretics are substances that aid the production of urine and thereby reduce blood pressure. Antidiuretics are hormones that control the blood pressure. They act on the blood vessels and the kidneys. They play a vital role in maintaining the volumes of the body fluids, and are often secreted during periods of dehydration and during excess salt levels in the body. When there are excessive amounts of antidiuretic hormone in the body, it leads to low salt content in the body, diseases of the lung, tumors, and excessive water retention. In cases of reduction of antidiuretic hormone secretion, it leads to excessive urination, and dehydration. In fact, low levels of antidiuretic hormone might indicate pituitary tumors, damage to the hypothalamus, or diabetes insipidus.