Diabetes insipidus

Diabetes insipidus (DI) is a disorder characterized by polydipsia, polyuria, and formation of inappropriately hypotonic (dilute) urine.

Two types exist: central DI, due to reduced synthesis or release of arginine vasopressin (AVP) from the hypothalamo-pituitary axis; and nephrogenic DI, due to renal insensitivity to AVP.

Recognized risk factors for central DI include pituitary surgery, craniopharyngioma, infiltrative pituitary stalk lesions, traumatic brain injury, subarachnoid hemorrhage, congenital hypothalamo-pituitary defects, autoimmune disorders, and Wolfram syndrome. Risk factors for nephrogenic DI include lithium therapy, chronic kidney disease, and chronic hypercalcemia or hypokalemia. Genetic mutations are responsible for inherited forms of both types.

Both types of DI may be associated with hypernatremia, and this may present as a medical emergency.

Treatment goals are correction and stabilization of water deficit and electrolyte balance, together with reduction in symptoms of excessive urinary water loss and thirst. In central DI, the synthetic AVP analog desmopressin (DDAVP) is the treatment of choice. Nephrogenic DI is treated with an adequate fluid intake; salt restriction and diuretics may help reduce polyuria.

Diabetes insipidus is a metabolic disorder characterized by an absolute or relative inability to concentrate urine, resulting in the production of large quantities of dilute urine. It may result from an absolute or relative deficiency of arginine vasopressin (AVP), also known as antidiuretic hormone (ADH), which is produced by the hypothalamus and secreted via the posterior pituitary, or by resistance to its action within the renal collecting ducts. Clinically it manifests as polydipsia, polyuria, and hypotonic urine.[1]Robinson A, Verbalis J. Posterior pituitary. In: Melmed S, Polonsky K, Larsen PR, et al, eds. Williams textbook of endocrinology. 13th ed. Philadelphia, PA: Elsevier; 2016:300-32.