Diabetes Insipidus
Background Information
Diabetes insipidus should not be confused with diabetes mellitus which is linked to high blood sugar. Diabetes insipidus is not. Diabetes insipidus is a disease that is caused by a decreased amount of ADH (the anti-diuretic hormone) which is also known as vasopressin.
The two main types of diabetes insipidus are central and nephrogenic.
Central diabetes insipidus occurs when there is a decreased production of ADH by the posterior pituitary. ADH is usually secreted by the posterior pituitary into the bloodstream where it acts upon the kidneys to maintain normal water balance. Patients with central diabetes insipidus may have the disease if they have pituitary tumors or infections because compression could occur or there could be side effects of surgical exploration. Patients having meningitis may have central diabetes insipidus.
Nephrogenic diabetes insipidus has a normal production of ADH, or even an increased production, yet the kidneys are resistant to the hormone. This kind of diabetes may be hereditary or may be brought on by such medicines as lithium.
Symptoms
Symptoms can occur quite abruptly, often after some form of trauma. When this occurs there is severe thirst, polyuria and nocturia. There is often a large output of dilute urine. There is often high volume urination at night of this watery urine and sometimes dehydration occurs with bouts of dizziness.
Diagnosis/Treatment
Your health care provider will usually take a twenty-four hour urine collection to measure the amount of urine produced. Then tests are conducted on both urine and blood to see if the kidneys are excreting their normal share of water.
A diagnostic test that has proved effective is called specific gravity. The specific gravity of urine in diabetes insipidus is unusually low. Also, the ADH level is measured because in central diabetes insipidus the ADH level is low. A dehydration test is also suggested and a MRI (magnetic resonance imaging scan) can show the lack of the posterior pituitary bright spots.
Unlike in central diabetes insipidus, the ADH or vasopressin level may be high or even normal in nephrogenic diabetes insipidus.
Fortunately diabetes insipidus, if caused by pressure on the posterior pituitary, is most likely curable. That is because the pressure is caused by a tumor which can then be removed. It also can resolve on its own after pituitary surgery. Sometimes certain medicines can cause diabetes and if the suspect medicine is discontinued diabetes insipidus most likely will resolve spontaneously.
However, sometimes the condition may be permanent. This can be a devastating illness if left untreated. Problems can include mental confusion, seizures, extremely elevated blood sodium, and even death. Patients with central diabetes insipidus usually respond well to the treatment of DDAVP (desmopressin). Your health care provider will want to follow you closely when you are taking this medication to watch for a decreased sodium level as well as to monitor your serum electrolytes.
Those patients diagnosed with nephrogenic diabetes insipidus should drink plenty of water when thirsty. The patients are usually able to adjust their serum sodium to normal levels based on their thirst. If the patients do not have access to water they need they may find they have an alarming elevation of sodium levels. Patients find that they are the most appropriate person to regulate their own serum sodium levels since it is based on each patient's natural thirst mechanisms. Soft drinks high in sodium are not recommended. It's usually best to stick with water. This condition should be closely monitored by your health care provider and team of medical experts. Your family members will also benefit from knowing all they can about this disease because they are most likely to notice any problems you might have such as a decreased ability to think normally or a worsening thirst or frequency of urination and can alert your health care provider and medical team.
If you have any questions about or feel you may have diabetes insipidus please see your health care provider promptly.
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