Dr. M.J. Bazos, MD Patient Handout


About Your Diagnosis

Diabetes insipidus is a disorder resulting from a decreased amount or action of the antidiuretic hormone (ADH), also known as vasopressin. Antidiuretic hormone is normally secreted by the posterior pituitary into the bloodstream where it acts upon the kidneys to maintain normal water balance. There are two main types of diabetes insipidus, central and nephrogenic. Central diabetes insipidus is caused by decreased production of ADH by the posterior pituitary. In nephrogenic diabetes insipidus, the production of ADH is normal or increased, but the kidneys are resistant to the effects of the hormone. Diabetes insipidus is a rare disorder except in
certain circumstances. Patients with hypothalamic or pituitary tumors or infections may have central diabetes insipidus as a result of compression or as a side effect of surgical exploration. Patients with head injuries or meningitis may have central diabetes insipidus as well. Nephrogenic diabetes insipidus may be a hereditary disorder or a result of medicines such as lithium. Diabetes insipidus is usually suspected in patients who have a large volume of dilute urine output and excessive thirst. A 24- hour urine collection is obtained to document the volume of urine produced. Special tests are performed on the urine and blood to determine whether the kidneys are excreting a normal amount of water. One test is the specific gravity. The specific gravity of urine is inappropriately low in diabetes insipidus. Once diabetes insipidus is diagnosed, the next step is to figure out the cause. If the medical history and physical examination do not reveal the answer, a vasopressin (ADH) level may be measured. In central diabetes insipidus, the vasopressin level is low. In nephrogenic diabetes insipidus, the vasopressin level is normal or high. Some patients may require a water deprivation test to see whether ADH is released normally in response to dehydration. If central diabetes insipidus is suspected, a magnetic resonance imaging (MRI) scan of the posterior pituitary will be performed, revealing an absence of the normal posterior pituitary bright spot. Diabetes insipidus is generally curable if it is caused by pressure on the posterior pituitary by a tumor. The cure is to remove the tumor. It may also be merely a transient condition after pituitary surgery that resolves spontaneously. If it is caused by a medicine and the medicine is stopped, the diabetes insipidus usually resolves. In other cases, however, the condition may be permanent. The symptoms may be ameliorated with certain treatments.

Living With Your Diagnosis
Symptoms include frequent urination of high volumes of very dilute, watery urine, urinating at night, extreme thirst (especially a desire for cold water), or dehydration with dizziness upon standing. Family members may notice behavioral changes if the patient has been unable to obtain enough water.
Untreated diabetes insipidus may lead to markedly elevated blood sodium, mental confusion, seizures, and death.

Patients with nephrogenic diabetes insipidus must stop any drugs that are exacerbating the condition and maintain a liberal intake of water whenever thirsty. Patients are able to autoregulate their serum sodium to normal levels based only on their thirst. Any attempts to restrict patients from access to water may result in severe elevation of sodium levels. Central diabetes insipidus is responsive to DDAVP (desmopressin) subcutaneously or as a nasal spray. This medicine is usually started once a day, although some patients require twice-a-day administration. Complications from this medicine include a decreased sodium from overtreatment. Serum electrolytes must be closely monitored.

The DOs
• Drink water whenever thirsty. You are the best person able to regulate your serum sodium based on your natural thirst mechanism.
• Take your medicine as prescribed.
• Allow several hours of increased urination and thirst at least every few days to avoid complications of hyponatremia (low serum sodium) from overtreatment with DDAVP.
• Find an experienced surgeon if you require surgery, to help minimize the risk of permanent diabetes insipidus.

The DON’Ts
• Don’t drink lots of high sodium-containing fluids such as soft drinks to relieve your thirst. This may lead to worsening symptoms. Instead, choose water.
• Don’t confuse diabetes insipidus with diabetes mellitus. Both may cause frequent urination, but diabetes mellitus is associated with a high blood sugar, whereas diabetes insipidus is not.

When to Call Your Doctor
• You notice unquenchable thirst.
• You or a family member notices a change in your ability to think.
• You have worsening frequency of urination despite treatment.
• You have high fever, diarrhea, or sweats.
• You are about to undergo elective surgery.