Diabetes insipidus (DI) is a rare condition characterized by excessive thirst and the production of large amounts of diluted urine. Unlike diabetes mellitus, which is caused by high blood sugar levels, diabetes insipidus is caused by a deficiency in the hormone vasopressin, which regulates the body's water balance.

DI can be caused by a number of factors, including genetic disorders, head injuries, tumors, infections, or damage to the hypothalamus or pituitary gland. In some cases, the cause is unknown.

Symptoms of DI can include excessive thirst and urine output, dehydration, and fatigue. Other symptoms may include irritability, muscle weakness, and weight loss.

Diagnosis of DI involves a physical examination, blood and urine tests, and imaging studies such as MRI. Treatment depends on the underlying cause of the condition. If DI is caused by a deficiency in vasopressin, it can be treated with synthetic vasopressin medications, such as desmopressin. If the cause is a tumor or other physical abnormality, surgery may be necessary.

DI is a rare condition, and early diagnosis and treatment are important to prevent complications such as dehydration and electrolyte imbalances. If you suspect you or someone you know has diabetes insipidus, it's important to seek medical advice from a healthcare professional who can determine the most appropriate course of treatment.

Diabetes insipidus occurs when your body can't properly balance the body's fluid levels.

Your kidneys filter the fluid portion of your blood to remove waste products. The majority of the fluid is returned to the bloodstream while the waste and a smaller amount of fluid make up urine. Urine is excreted from your body after being temporarily stored in your bladder.

A hormone called anti-diuretic hormone (ADH), or vasopressin, is needed for the fluid that's filtered by the kidneys to go back into the bloodstream. ADH is made in a part of the brain called the hypothalamus and stored in the pituitary gland, a small gland found in the base of the brain. Conditions that cause a deficiency of ADH or block the effect of ADH result in production of excess urine.

If you have diabetes insipidus, your body can't properly balance fluid levels. The cause depends on the type of diabetes insipidus you have. Types include:

• Central diabetes insipidus. Damage to the pituitary gland or hypothalamus from surgery, a tumor, head injury or illness can cause central diabetes insipidus by affecting the usual production, storage and release of ADH. An inherited genetic disease also can cause this condition.
• Nephrogenic diabetes insipidus. Nephrogenic diabetes insipidus occurs when there's a defect in the structures in your kidneys that makes your kidneys unable to properly respond to ADH.
• The defect may be due to an inherited (genetic) disorder or a chronic kidney disorder. Certain drugs, such as lithium or antiviral medications such as foscarnet (Foscavir), also can cause nephrogenic diabetes insipidus.
• Gestational diabetes insipidus. Gestational diabetes insipidus is rare. It occurs only during pregnancy when an enzyme made by the placenta destroys ADH in the mother.
• Primary polydipsia. Also known as dipsogenic diabetes insipidus, this condition can cause production of large amounts of diluted urine from drinking excessive amounts of fluids.
• Primary polydipsia can be caused by damage to the thirst-regulating mechanism in the hypothalamus. The condition has also been linked to mental illness, such as schizophrenia.

Sometimes, there's no obvious cause of diabetes insipidus. However, in some people, the disorder may be the result of an autoimmune reaction that causes the immune system to damage the cells that make vasopressin.

Treatment options depend on the type of diabetes insipidus you have.

• Central diabetes insipidus. If you have mild diabetes insipidus, you may need only to increase your water intake. If the condition is caused by an abnormality in the pituitary gland or hypothalamus (such as a tumor), your doctor will first treat the abnormality.
• Typically, this form is treated with a synthetic hormone called desmopressin (DDAVP, Nocdurna). This medication replaces the missing anti-diuretic hormone (ADH) and decreases urination. You can take desmopressin in a tablet, as a nasal spray or by injection.
• Most people still make some ADH, though the amount can vary day to day. So, the amount of desmopressin you need also may vary. Taking more desmopressin than you need can cause water retention and potentially serious low-sodium levels in the blood.
• Other medications might also be prescribed, such as chlorpropamide. This can make ADH more available in the body.
• Nephrogenic diabetes insipidus. Since the kidneys don't properly respond to ADH in this form of diabetes insipidus, desmopressin won't help. Instead, your doctor may prescribe a low-salt diet to reduce the amount of urine your kidneys make. You'll also need to drink enough water to avoid dehydration.
• Treatment with the drug hydrochlorothiazide (Microzide) may improve your symptoms. Although hydrochlorothiazide is a type of drug that usually increases urine output (diuretic), it can reduce urine output for some people with nephrogenic diabetes insipidus.
• If your symptoms are due to medications you're taking, stopping these medicines may help. However, don't stop taking any medication without first talking to your doctor.
• Gestational diabetes insipidus. Treatment for most people with gestational diabetes insipidus is with the synthetic hormone desmopressin.
• Primary polydipsia. There is no specific treatment for this form of diabetes insipidus, other than decreasing fluid intake. If the condition is related to a mental illness, treating the mental illness may relieve the diabetes insipidus symptoms.