Diabetes Insipidus

Diabetes insipidus (DI) is an endocrine disorder involving deficient production or lack of effective action of an antidiuretic hormone (ADH or vasopressin).  ADH is made in the hypothalamus, stored in and secreted by the pituitary gland and works on the kidney to conserve fluid.  Deficient production of ADH or lack of effective action of ADH at the kidney causes large amount of urine output, increasing thirst, dehydration, and low blood pressure in advanced cases.  While the average urine volume for a normal adult is 1.5 liters daily, it can approach 18 liters daily in cases of DI.

When diseases of the hypothalamus and pituitary gland cause reduced ADH production, it is called central DI.  When diseases of the kidney cause a lack of response to ADH it is called nephrogenic DI.

Causes and Development

Causes of central DI include surgical removal of the hypothalamus, tumors of the hypothalamus or the pituitary gland, infection of the pituitary gland, autoimmune damage of the pituitary gland, and familial disease of the pituitary gland.

Causes of nephrogenic DI include certain kidney diseases and can be influenced by low blood potassium level, protein starvation, high blood calcium level, sickle cell anemia and medication use (such as lithium, demeclocycline and methoxyflurane).

Diagnosis and Tests

Diagnosis of DI involves excluding other conditions producing large urine volumes, lab testing for ADH and other tests to determine the cause.

Treatment and Prevention

Treatment of central DI involves administering the missing ADH hormone orally, by injection or by inhalation nasally.

Prognosis

Properly treated, patients with central DI can restore urine volume towards normal levels and do well.  Long-term prognosis of many patients with central DI are good, some actually spontaneously improve over time.  To achieve optimal outcome, it is important for patients to work closely with their doctors to accurately diagnose the condition, identify the underlying cause, and start treatment.