Dr. M.J. Bazos, MD
Patient Handout
DIABETES
INSIPIDUS
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.
Treatment
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.