Central diabetes insipidus
Central diabetes insipidus is a disorder that is characterized by excessive thirst and excessive urination. It is caused by a lack of the hormone, vasopressin (also called antidiuretic hormone). This absence results in the kidneys releasing excessive amounts of water from the body. Control of this disorder is possible with medication.
Definition & Facts
Central diabetes insipidus occurs when the body does not make enough of a natural hormone known as vasopressin. Vasopressin is a hormone secreted by the pituitary gland. It signals the kidneys to retain water and to maintain blood pressure. When there is not enough vasopressin released to the body, the kidneys discharge all the water that passes through as urine.
The body loses a lot of water and can easily become dehydrated. Central diabetes insipidus is different from the diabetes that people commonly know. Although both stem from a lack of a hormone, it is a different hormone and a different outcome. Central diabetes insipidus is a rare condition, occurring in only one out of every 25,000 people.
Symptoms & Complaints
The most significant sign of the disorder is the frequent urination that occurs. Because the kidneys are not functioning properly, the body loses a lot of water very quickly. This frequent urination often disturbs sleep, causing patients to wake up multiple times during the night to use the bathroom. In some cases, involuntary urination during sleep causes bedwetting. Moreover, the urine is usually very dilute, pale, or colorless.
Along with excessive urination, a person with central diabetes insipidus will also be very thirsty and drink a lot, sometimes upwards of a gallon of liquid each day. If the disease becomes severe, or if a person cannot get enough to drink, it can lead to dehydration. Dehydration can then lead to difficulty concentrating, memory loss, and loss of consciousness.
A small number of the cases of central diabetes insipidus may be inherited as autosomal dominant or autosomal recessive traits. These seem to be the exception since more cases are caused by some sort of trauma to the hypothalamus, pituitary gland, or the connections between the two.
The hypothalamus is a part of the brain that acts as a link between the brain and the endocrine system. It actually releases the vasopressin in a healthy individual. It then travels to the posterior portion of the pituitary gland where it is stored until it is needed. When any of these are injured or disturbed, vaspressin production, transport, storage, or release may be disrupted, causing the symptoms of central diabetes insipidus.
Problems may occur because of accidents, during surgery, particularly to remove a brain tumor, from certain infections, from certain rare diseases, and from certain inflammatory diseases, vascular diseases, or granulomatous diseases. Additionally, researchers think that central diabetes insipidus may sometimes be caused by an autoimmune disease where the body “attacks” its own healthy tissues. Finally, there is evidence that the disorder may appear as one part of a larger disease such as Wolfram syndrome and others.
Diagnosis & Tests
Central diabetes insipidus may be suspected by a doctor if the characteristic signs and symptoms such as excessive urination and excessive thirst are present. To help confirm this, a doctor will perform a complete medical exam including asking about the patient's medical history. Patients will want to discuss any possible head injuries or surgeries they may have had.
A magnetic resonance imaging (MRI) of the head may be conducted to detect any damage to the hypothalamus or pituitary gland as well as detect any tumor growths. Additionally, clinical urine tests and blood tests will likely be done. The urine is first tested for excess sugar to rule out diabetes, which also has excessive urination as a symptom. Blood tests can reveal high electrolyte levels and high levels of sodium.
The most conclusive test for central diabetes insipidus, however, is a fluid deprivation test. This test must be performed under constant medical supervision since it is possible for the patient to become severely dehydrated. For this test, a patient cannot drink any liquid for a period of at least 12 hours. During this time, the patient’s urine output, body weight, and blood electrolyte levels are carefully monitored.
After the period is up, the doctor administers an injection of vasopressin. Diagnosis is confirmed if, in response to the vasopressin, the patient’s excessive urination stops, urine becomes more concentrated, and blood pressure and heart rate become more normal.
Treatment & Therapy
Controlling the excessive urination and ensuring proper hydration is essential to treating this disorder. Depending on the severity of the condition, it may be treated in several ways. For those with milder cases who still produce some vasopressin, medications that stimulate the release of vasopressin may be prescribed.
Other patients cannot produce any vasopressin, and thus they must be given hormone replacement therapy. This may be in the form of a nasal spray or a tablet. If the person is unconscious, vasopressin injections can be dispensed. The amount of vasopressin an individual needs will be carefully determined and monitored to keep the patient from becoming dehydrated.
In addition, if too much is given, there will be water retention which can cause swelling, raise blood pressure, and damage the heart. Nevertheless, with proper dosage, a person can control this disorder.
Prevention & Prophylaxis