The patients of diabetes insipidus present to the hospital with the complaint of polyuria and/or dehydration. The patient may pass 5 to 20 or even more liters of urine in 24 hours. The urine has a very low specific gravity and osmolality.
As the patient loses a lot of water, signs of dehydration start appearing. The mouth becomes dry and the skin loses its elasticity. The patient also has excessive thirst (polydipsia).
The diagnosis of diabetes insipidus is established by the use of the following investigations .
Central diabetes insipidus
An analog of antidiuretic hormone called desmopressin is the treatment of choice for central diabetes insipidus. The bioavailability of desmopressin in oral form is negligible. Therefore, it is usually given in the form of nasal spray. It may also be given intramuscularly if the patient is acutely ill .
Thiazide diuretics have a paradoxical effect and decrease polyuria in both central and nephrogenic diabetes insipidus. A combination of indomethacin and hydrochlorothiazide or indomethacin and amiloride may be used in nephrogenic diabetes   . In addition, the use of low salt diet may be advised to reduce thirst and to lower the excretion of water.
With proper treatment, the prognosis for the people suffering from diabetes insipidus is excellent. Central diabetes insipidus responds to treatment much more easily than nephrogenic diabetes insipidus.
Although the patients of diabetes insipidus rapidly become dehydrated, mortality from it is rare in previously healthy adult patients. Children and the elderly are at a higher risk of mortality from severe dehydration.
Diabetes insipidus is of two types, central and nephrogenic.
Central diabetes insipidus
Central diabetes insipidus results from deficient production of antidiuretic hormone (ADH) in the hypothalamus or their inability to reach the posterior pituitary from where they are released in the blood . It is most commonly associated with hypothalamic or high stalk lesions such as craniopharyngioma, sarcoidosis, histiocytosis X, tuberculous meningitis, encephalitis and syphilis . Head injuries and surgeries may also cause damage to the hypothalamus. Pituitary tumors with suprasellar extension or metastases to the pituitary may also cause central diabetes insipidus. Central diabetes insipidus may also have idiopathic or genetic etiologies .
It results from the lack of response of renal tubules to antidiuretic hormone . It is associated with renal damage with may result from genetic defects (sex linked recessive defects, cystinosis), metabolic abnormalities (such as hypokalemia and hypercalcemia), drug therapy (with lithium or demeclocycline) or heavy metal poisoning. It may also be caused by other conditions such as pyelonephritis, renal amyloidosis, multiple myeloma and Sjogren syndrome.
Not much data is available regarding the epidemiology of diabetes insipidus. However, it is a rare disease with a prevalence of 3 per 100,000 people in the United States . The prevalence is equal in men and women. Various ethnic groups also have equal tendencies for the development of diabetes insipidus.
Antidiuretic hormone is a nonpeptide hormone that is formed in the hypothalamus and stored in the posterior pituitary. Its primary effect is on the epithelial cells of the renal collecting tubules where it augments the resorption of water independently of the solutes. This causes dilution of the blood serum and concentration of the urine.
Diabetes insipidus results due to a decreased effect of antidiuretic hormone. The cause may be central or nephrogenic. Central diabetes insipidus results from an ineffective production of antidiuretic hormone; whereas in nephrogenic diabetes insipidus, the cells of the kidney fail to respond to it.
There are no documented ways to prevent the development of diabetes insipidus.
Diabetes insipidus is an endocrine disease characterized by the persistent excretion of excessive quantities of dilute urine and constant, excessive thirst. It results from a decreased action of antidiuretic hormone - the posterior pituitary hormone that is responsible for the suppression of urination by increasing the resorption of water in the renal collecting tubules. It may be due to a decreased production of antidiuretic hormone or the inability of the renal cells to respond to it.
Diabetes insipidus is treated by the administration of desmopressin (an analog of antidiuretic hormone) along with thiazide diuretics. The disease is fatal unless adequate rehydration and proper treatment is ensured.
The pituitary gland is a small gland located at the base of the brain. One of the hormone it secretes is called antidiuretic hormone. This hormone acts on the kidneys and causes absorption of water back into the blood, thereby preventing the excessive loss of water in the urine. In diabetes insipidus, there is either a reduced production or inadequate effect of antidiuretic hormone which causes the loss of a large amount of water in the urine. The patients develop dehydration and excessive thirst. With proper treatment, there is an excellent control of the disease.