Diabetes insipidus - nephrogenic

Definition

Nephrogenic diabetes insipidus is a disorder in which a defect in the small tubes (tubules) in the kidneys causes a person to pass a large amount of urine. The tubules allow water to be removed from the body or reabsorbed.

See also: Diabetes insipidus - central

Alternative Names

Nephrogenic diabetes insipidus; Acquired nephrogenic diabetes insipidus; Congenital diabetes insipidus

Causes, incidence, and risk factors

Nephrogenic diabetes insipidus occurs when the kidney tubules do not respond to a chemical in the body called antidiuretic hormone (ADH), also called vasopressin. ADH normally tells the kidneys to make the urine more concentrated.

As a result of the defect, the kidneys release an excessive amount of water into the urine, producing a large quantity of very dilute urine. This makes you produce large amounts of urine.

Nephrogenic diabetes insipidus is rare. Congenital diabetes insipidus is 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 develops because of other reasons. This is called an acquired disorder. Factors that can trigger the acquired form of this condition include:

• Blockage in the urinary tract
• High calcium levels
• Low potassium levels
• Use of certain drugs (lithium, demeclocycline, amphotericin B)

Symptoms

You may have intense or uncontrollable thirst, and crave ice water. You will produce large amounts of urine, usually more than 3 - 15 liters per day.

If you do not drink enough fluids, dehydration can result. Symptoms may include:

• Dry mucous membranes
• Dry skin
• Sunken appearance to eyes
• Sunken fontanelles (soft spot) in infants

Other symptoms that can occur due to inadequate fluids include:

• Fatigue, lethargy
• Headache
• Irritability
• Low body temperature
• Muscle pains
• Rapid heart rate
• Weight loss

Signs and tests

A physical exam may reveal:

• Low blood pressure
• Rapid pulse
• Shock
• Signs of dehydration

Testing may reveal:

• High serum osmolality
• High urine output, regardless of how many fluids you drink
• Kidneys don't concentrate urine when the person is given ADH
• Low urine osmolality
• Normal or high ADH levels

Other tests that may be done include:

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

Treatment

The goal of treatment is to control the body's fluid levels. Patients will be given a large amount of fluids. The amount of fluids given should be about equal to the amount of urine produced.

If the condition is due to a certain medication, stopping the medicine may improve symptoms. Never stop taking any medication without first talking to your doctor.

A medicine called 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.

Expectations (prognosis)

If a person drinks enough fluids, this condition has no significant effects on the fluid or electrolyte balance of the body.

If the person does not drink enough fluids, high urine output may cause dehydration and high levels of sodium in the blood.

Nephrogenic diabetes insipidus that is present at birth is a chronic condition requiring lifelong treatment.

Complications

• Dilation of the ureters and bladder
• High blood sodium (hypernatremia)
• Severe dehydration
• Shock

Calling your health care provider

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

Prevention

There is no known way to prevent congenital nephrogenic diabetes insipidus.

Treating the disorders that can lead to the acquired form of the condition may prevent it from developing in some cases. Medications should only be used under the supervision of the health care provider.

References

Verbalis JG. Posterior pituitary. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 243.