ADAM Health Encyclopedia

Diabetes insipidus - nephrogenic

Definition

Nephrogenic diabetes insipidus is a disorder in which a defect of the small tubes (tubules) in the kidneys results in the passage of large volumes of urine.

See also: Diabetes insipidus-central

Alternative Names

Causes

Nephrogenic diabetes insipidus involves a defect in the kidney tubules (the portion of the kidneys that causes water to be excreted or reabsorbed). The defect affects the ability of the kidneys to respond to antidiuretic hormone (ADH; vasopressin), which normally instructs the kidneys to make the urine more concentrated.

As a result, the kidneys excretes an excessive amount of water into the urine, producing a large quantity of very dilute urine.

Nephrogenic diabetes insipidus is a rare disorder. It may be present at birth as a result of an inherited defect that usually affects men, although women can pass the gene on to their children.

Most commonly, nephrogenic diabetes insipidus is an acquired disorder. Factors that can bring on the disorder include:

• Drugs (lithium, demeclocycline, amphotericin B)
• Electrolyte disorders (high calcium or low potassium levels)
• Urinary blockage

Symptoms

If a person has normal thirst mechanisms and drinks enough fluids, this condition has no significant effects on the fluid and/or electrolyte balance of the body. If the person does not drink enough fluids, the high urine output may cause dehydration and high blood sodium.

Symptoms include:

• Excessive thirst (may be intense or uncontrollable, with a craving for ice water)
• Excessive urine volume (may exceed 3 - 15 liters per day)

• Dehydration
  • Dry mucus membranes
  • Dry skin
  • Sunken appearance to eyes
  • Sunken fontanelles (soft spot) in infants
• Fatigue, lethargy
• Headache
• Irritability
• Low body temperature
• Muscle pains
• Rapid heart rate
• Weight loss

Exams and Tests

Examination may reveal:

• Dehydration and/or shock
• High urine output, regardless of fluid intake
• Low blood pressure
• Rapid pulse rate

Signs associated with high urine output are:

• High serum osmolality
• Kidneys don't concentrate urine when the person is given ADH
• Low urine osmolality
• Normal or high ADH levels

This disease may also affect the results of the following tests:

• Serum sodium
• Urine 24h volume
• Urine concentration test
• Urine specific gravity

Treatment

The goal of treatment is to regulate fluid levels in the body. Treatment should involve high fluid intake. The volume of fluids consumed should be about equal to the volume of urine produced.

Reducing or stopping medications that can cause nephrogenic DI may improve symptoms.

Hydrochlorothiazide may improve symptoms. This may be used alone or in combination with other medications, including indomethacin. Although this medication is a diuretic (these medications are usually used to increase urine output), in certain cases hydrochlorothiazide can actually reduce urine output for people with nephrogenic diabetes insipidus.

Outlook (Prognosis)

Congenital nephrogenic DI is a chronic condition requiring lifelong treatment. Acquired nephrogenic DI may be short-term or long-term.

Possible Complications

• Dilation of the ureters and bladder
• High blood sodium (hypernatremia)
• Severe dehydration, shock (if inadequate fluid intake)

When to Contact a Medical Professional

Call your health care provider if you have symptoms of nephrogenic diabetes insipidus.

Prevention

There is no known way to prevent nephrogenic diabetes insipidus that occurs at birth (congenital). Treating the disorders that cause it may prevent some cases of the acquired form of the condition. Medications should only be used under the supervision of the health care provider.