Diabetes insipidus is a rare disorder where the system the body uses to regulate its water levels becomes disrupted. This disruption leads to the two most common symptoms of diabetes insipidus:
- excessive and prolonged thirst
- passing large amounts of urine and needing to urinate frequently
Left untreated, diabetes insipidus can result in severe dehydration, shock (a sudden drop in blood pressure) and, in particularly vulnerable people, death.
Antidiuretic hormone (ADH)
The amount of water in the body is regulated by a hormone called antidiuretic hormone (ADH), also known as vasopressin. ADH is made by a part of the brain called the hypothalamus and is stored just below the brain, in the pituitary gland, until it is needed.
When the amount of water in the body becomes too low, ADH is released from the pituitary gland.
This helps to retain water in the body by stopping the kidneys from producing urine.
However, in diabetes insipidus, ADH does not stop the kidneys from producing urine and allows too much water to be passed from the body. This results in symptoms such as needing to pass large quantities of urine often and feeling extremely thirsty all the time. See Diabetes insipidus – symptoms for more information.
Types of diabetes insipidus
There are two main types of diabetes insipidus, which are described below.
Cranial diabetes insipidus
Cranial diabetes insipidus occurs when there is not enough ADH in the body to regulate the amount of urine that is produced.
This is the most common type of diabetes insipidus and can be caused by damage to the hypothalamus or pituitary gland, for example after an infection, operation or head injury.
In an estimated 30% of cases of cranial diabetes insipidus, the cause of the condition is unknown.
Nephrogenic diabetes insipidus
Nephrogenic diabetes insipidus occurs when there is enough ADH in the body but the kidneys fail to respond to it. It can run in families or it can be caused by kidney damage.
Some medications, especially lithium (used in the treatment of a number of serious mental health conditions, such as bipolar disorder), have been known to cause nephrogenic diabetes insipidus.
How common is diabetes insipidus?
Diabetes insipidus is a rare condition, affecting an estimated 1 in 25,000 people. As the condition is usually acquired through injury or infection, it can affect people of all ages.
Outlook
The outlook for diabetes insipidus can vary widely depending on the underlying cause.
If it is diagnosed quickly before dehydration occurs, the outlook is moderate to good.
The symptoms of cranial central diabetes insipidus can usually be controlled with medication, while changes to diet are used to help treat nephrogenic diabetes. For more information, see Diabetes insipidus – treatment.
