Antidiuretic hormone (ADH) is manufactured by the hypothalamus, secreted by the posterior lobe of the pituitary gland, and controls the amount of water reabsorbed by the kidneys . An increase in serum osmotic pressure or a decrease in blood volume triggers ADH release . Circulating ADH targets kidney cells and more water is reabsorbed, thereby increasing blood volume. Antidiuretic hormone is also known as vasopressin because it causes constriction of arterioles, which in turn raises blood pressure.
Variations from Normal.
Increased serum levels of antidiuretic hormone give rise to syndrome of inappropriate ADH secretion (SIADH), a condition marked by inappropriately high levels of ADH secretion. The high levels of antidiuretic hormone cause an excess amount of water to be reabsorbed by the kidneys, which in turn affects the body's fluid and electrolyte balance . Alterations of individual electrolytes can affect neurologic, cardiac, and metabolic functions. Diseases related to SIADH include cancer of the lung, thymus, pancreas, and urologic tract. Lymphomas, leukemia, several pulmonary diseases, and brain tumors can also exhibit SIADH. Inadequate or decreased secretion of antidiuretic hormone is seen in diabetes insipidus. It must be noted that diabetes insipidus can also be caused by the kidney's inability to respond to ADH stimulation. Trauma, tumor, and inflammation of the brain, or surgical removal of the pituitary gland, cause insufficient ADH secretion.
Interfering Circumstances.
Dehydration, decreased blood volume, and stress may cause increased antidiuretic hormone levels. Drugs related to increased levels include acetaminophen, barbiturates, estrogen, nicotine, some diuretics, and tricyclic antidepressants. Overhydration and increased blood volume may cause decreased ADH levels. Drugs related to decreased levels include alcohol, morphine antagonists, and phenytoin.
Normal Range: 1-5 pg/mL