Diabetes insipidus

Symptoms of diabetes insipidus

The two main symptoms of diabetes insipidus are:

• extreme thirst (polydipsia)
• passing large amounts of urine, even at night (polyuria) – more than three litres in 24 hours is considered abnormal

In very severe cases of diabetes insipidus, passing 15 litres of urine in a day can occur.

When to seek medical advice

You should always see your GP if you're feeling thirsty all the time. Although it may not be diabetes insipidus, it should be investigated.

Also see your GP if you're:

• passing more urine than normal – most healthy adults pass urine four to seven times in a 24 hour period
• passing small amounts of urine at frequent intervals – sometimes, this can occur along with the feeling that you need to pass urine immediately

Children tend to urinate more often because they have smaller bladders. However, seek medical advice if your child urinates more than 10 times a day.

Your GP will be able to carry out a number of tests to help work out what's causing the problem.

Causes of diabetes insipidus

Diabetes insipidus is caused by problems with a hormone called vasopressin (AVP), also called antidiuretic hormone (ADH).

AVP is produced by specialist nerve cells in a part of the brain known as the hypothalamus. AVP passes from the hypothalamus to the pituitary gland where it's stored until needed.

The pituitary gland releases AVP when the amount of water in the body becomes too low. It helps retain water in the body by reducing the amount of water lost through the kidneys, producing more concentrated urine.

In diabetes insipidus, the lack of production of AVP means the kidney can't make enough concentrated urine and too much water is passed from the body. In rare cases, the kidney doesn't respond to AVP.

People feel thirsty as the body tries to compensate for the increased loss of water by increasing the amount of water taken in.

People affected by diabetes insipidus

Adults are more likely to develop the condition but it can occur at any age. In rarer cases, diabetes insipidus can develop during pregnancy, known as gestational diabetes insipidus.

Types of diabetes insipidus

There are two main types of diabetes insipidus:

• cranial diabetes insipidus
• nephrogenic diabetes insipidus

Cranial diabetes insipidus

Cranial diabetes insipidus occurs when there's not enough AVP in the body to regulate urine production. It’s the most common type of diabetes insipidus. It can be caused by damage to the hypothalamus or pituitary gland.

In about one in three cases of cranial diabetes insipidus there's no obvious reason why the hypothalamus stops making enough AVP.

Nephrogenic diabetes insipidus

Nephrogenic diabetes insipidus occurs when there's enough AVP in the body but the kidneys fail to respond to it.

It can be caused by:

• kidney damage
• inherited as a problem on its own
• Some medications, particularly lithium (used to help stabilise mood in some people with specific mental health conditions)

Treating diabetes insipidus

Treatment isn't always needed for mild cases of cranial diabetes insipidus. You just need to increase the amount of water you drink to compensate for the fluid lost through urination.

If necessary, a medication called desmopressin can be used to replicate the functions of AVP.

Nephrogenic diabetes insipidus is often treated with medications. These reduce the amount of urine the kidneys produce. The doctor treating you will discuss the best treatment option for you.

Complications

As diabetes insipidus increases water loss in the urine, the amount of water in the body can become low. This is known as dehydration.

Rehydration with water can be used to treat mild dehydration. Severe dehydration will need to be treated in hospital.

• Find out more about diabetes insipidus on the NHS website

More useful links

• How to use your health services