diabetes insipidus /insip″idəs/ , a metabolic disorder caused by injury of the neurohypophyseal system. It is characterized by copious excretion of urine and excessive thirst, caused by deficient production or secretion of the antidiuretic hormone (ADH) or inability of the kidney tubules to respond to ADH. Rarely the symptoms are self-induced by an excessive water intake. The condition may be acquired, familial, idiopathic, neurogenic, nephrogenic, or psychogenic. ▪ OBSERVATIONS: The onset may be dramatic and sudden, and urinary output may exceed 10 L in 24 hours. Diagnosis is established by a water deprivation test in which urine volume increases and urine osmolality decreases. A person with diabetes insipidus who is unconscious as result of trauma or surgery continues to produce massive quantities of urine. If fluids are not administered in adequate amounts, the patient becomes severely dehydrated and hypernatremic. ▪ INTERVENTIONS: In mild cases, no treatment is necessary. Vasopressin in an intramuscular injection or nasal spray is effective. Thiazide diuretics, by inducing a state of salt depletion, sometimes decrease the diuresis of water by as much as 50%. ▪ PATIENT CARE CONSIDERATIONS: Infants, small children, and the elderly are particularly vulnerable to serious circulatory disturbances when dehydrated. Exceedingly careful monitoring is essential when the condition is suspected, especially after head surgery or trauma.
