The 2 main symptoms of diabetes insipidus are often needing to pee a large amount of urine and feeling extremely thirsty.

If you have diabetes insipidus, you may pee pale, watery urine every 15 to 20 minutes.

The amount of urine can range from 3 litres in mild cases to up to 20 litres per day in severe cases.

It's also likely that you'll feel thirsty all the time and have a "dry" feeling that's always present, no matter how much water you drink.

If you need to pee regularly and always feel thirsty, your sleeping patterns and daily activities may be disrupted.

This can cause tiredness, irritability and difficulty concentrating, which can affect your daily life further.

You may also feel generally unwell and "run down" much of the time for no apparent reason.

Symptoms in children

Excessive thirst can be difficult to recognise in children who are too young to speak.

Signs and symptoms that could suggest diabetes insipidus include:

• excessive crying
• irritability
• slower than expected growth
• high body temperature (hyperthermia)
• unexplained weight loss 

In older children, symptoms of diabetes insipidus include:

• wetting the bed (enuresis) – although most children who wet the bed do not have diabetes insipidus
• loss of appetite
• feeling tired all the time (fatigue)

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

AVP is produced by the hypothalamus and stored in the pituitary gland until needed.

The hypothalamus is an area of the brain that controls mood and appetite.

The pituitary gland is located below your brain, behind the bridge of your nose.

AVP regulates the level of water in your body by controlling the amount of urine your kidneys produce.

When the level of water in your body decreases, your pituitary gland releases AVP to conserve water and stop the production of urine.

In diabetes insipidus, AVP fails to properly regulate your body's level of water, and allows too much urine to be produced and passed from your body.

There are 2 main types of diabetes insipidus:

• cranial diabetes insipidus – where the body does not produce enough AVP, so excessive amounts of water are lost in large amounts of urine
• nephrogenic diabetes insipidus – where AVP is produced at the right levels, but, for a variety of reasons, the kidneys do not respond to it in the normal way

Cranial diabetes insipidus

The 3 most common causes of cranial diabetes insipidus are:

• a brain tumour that damages the hypothalamus or pituitary gland
• a severe head injury that damages the hypothalamus or pituitary gland
• complications that occur during brain or pituitary surgery

No cause can be found for about a third of all cases of cranial diabetes insipidus.

These cases, known as idiopathic, appear to be related to the immune system attacking the normal healthy cells producing AVP.

It's unclear what causes the immune system to do this.

Less common causes of cranial diabetes insipidus include:

• cancers that spread from another part of the body to the brain
• Wolfram syndrome, a rare genetic disorder that also causes vision loss
• brain damage caused by a sudden loss of oxygen, which can occur during a stroke or drowning
• infections, such as meningitis and encephalitis, that can damage the brain

Nephrogenic diabetes insipidus

Your kidneys contain nephrons, which are tiny intricate structures that filter waste products from the blood and help produce urine.

They also control how much water is reabsorbed into your body and how much is passed in the urine when you pee.

In a healthy person, AVP acts as a signal to the nephrons to reabsorb water into the body.

In nephrogenic diabetes insipidus, the nephrons in the kidneys are not able to respond to this signal, leading to excessive water loss in large amounts of urine.

Your thirst increases to try to balance this loss from the body.

Nephrogenic diabetes insipidus can be present at birth (congenital) or develop later in life as a result of an external factor (acquired).

These are described in more detail below.

Congenital nephrogenic diabetes insipidus

Two abnormal changes in genes that leads to them not working properly (genetic mutations) have been identified that cause congenital nephrogenic diabetes insipidus.

The first, known as the AVPR2 gene mutation, is responsible for 90% of all cases of congenital diabetes insipidus.

But it's still rare, occurring in an estimated 1 in 250,000 births.

The AVPR2 gene mutation can only be passed down by mothers (who may appear to not be affected) to their sons (who are affected).

The remaining 10% of cases of congenital nephrogenic diabetes insipidus are caused by the AQP2 gene mutation, which can affect both males and females.

Find out more about genetics

Acquired nephrogenic diabetes insipidus

Lithium is the most common cause of acquired nephrogenic diabetes insipidus.

It's a medication often used to treat bipolar disorder.

Long-term lithium use can damage the cells of the kidneys so they no longer respond to AVP.

Just over half of all people on long-term lithium therapy develop some degree of nephrogenic diabetes insipidus.

Stopping lithium treatment often restores normal kidney function, although in many cases the damage to the kidneys is permanent.

Because of these risks, it's recommended that you have kidney function tests every 3 months if you're taking lithium.

Find out more about the treatment of bipolar disorder

Other causes of acquired nephrogenic diabetes insipidus include:

• hypercalcaemia – a condition where there's too much calcium in the blood (high calcium levels can damage the kidneys)
• hypokalemia – a condition where there's not enough potassium in the blood (all the cells in the body, including kidney cells, require potassium to function properly)
• pyelonephritis (kidney infection) – where the kidneys are damaged by an infection
• ureteral obstruction – where 1 or both tubes that connect the kidneys to the bladder (ureters) become blocked by an object, such as a kidney stone, which damages the kidneys

See your GP if you have the symptoms of diabetes insipidus. They'll ask about your symptoms and carry out a number of tests.

You may be referred to an endocrinologist (a specialist in hormone conditions) for these tests.

As the symptoms of diabetes insipidus are similar to those of other conditions, including type 1 diabetes and type 2 diabetes, tests will be needed to confirm which condition you have.

If diabetes insipidus is diagnosed, the tests will also be able to identify the type you have (cranial or nephrogenic).

Water deprivation test

A water deprivation test involves not drinking any liquid for several hours to see how your body responds.

If you have diabetes insipidus, you'll continue to pee large amounts of dilute urine when normally you'd only pee a small amount of concentrated urine.

During the test, the amount of urine you produce will be measured.

You may also need a blood test to assess the levels of antidiuretic hormone (ADH) in your blood.

Your blood and urine may also be tested for substances such as glucose (blood sugar), calcium and potassium.

If you have diabetes insipidus, your urine will be very dilute, with low levels of other substances.

A large amount of sugar in your urine may be a sign of type 1 or type 2 diabetes rather than diabetes insipidus.

Vasopressin test

After the water deprivation test, you may be given a small dose of AVP, usually as an injection.

This will show how your body reacts to the hormone, which helps to identify the type of diabetes insipidus you have.

If the dose of AVP stops you peeing urine, it's likely your condition is the result of a shortage of AVP.

If this is the case, you may be diagnosed with cranial diabetes insipidus.

If you continue to pee despite the dose of AVP, this suggests there's already enough AVP in your body, but your kidneys are not responding to it.

In this case, you may be diagnosed with nephrogenic diabetes insipidus.

MRI scan

An MRI is a type of scan that uses a strong magnetic field and radio waves to produce images of the inside of the body, including your brain.

You may need an MRI scan if your endocrinologist thinks you have cranial diabetes insipidus as a result of damage to your hypothalamus or pituitary gland.

If your condition is caused by an abnormality in your hypothalamus or pituitary gland, it may need to be treated too, along with treatment for diabetes insipidus.

Treatments for diabetes insipidus aim to reduce the amount of urine your body produces.

Depending on the type of diabetes insipidus you have, there are several ways of treating your condition and controlling your symptoms.

Cranial diabetes insipidus

Mild cranial diabetes insipidus may not require any medical treatment.

Cranial diabetes insipidus is considered mild if you produce approximately 3 to 4 litres of urine over 24 hours.

If this is the case, you may be able to ease your symptoms by increasing the amount of water you drink to avoid dehydration.

Your GP or endocrinologist (a specialist in hormone conditions) may advise you to drink a certain amount of water every day, usually at least 2.5 litres.

But if you have more severe cranial diabetes insipidus, drinking water may not be enough to control your symptoms.

As your condition is caused by a shortage of vasopressin (AVP), your GP or endocrinologist may prescribe a treatment that takes the place of AVP, known as desmopressin.

Desmopressin

Desmopressin is a manufactured version of AVP that's more powerful and more resistant to being broken down than the AVP naturally produced by your body.

It works just like natural AVP, stopping your kidneys producing urine when the level of water in your body is low.

Desmopressin can be taken as a nasal spray, in tablet form or as a form that melts in your mouth, between your gum and your lip.

If you're prescribed desmopressin as a nasal spray, you'll need to spray it inside your nose once or twice a day, where it's quickly absorbed into your bloodstream.

If you're prescribed desmopressin tablets, you may need to take them more than twice a day.

This is because desmopressin is absorbed into your blood less effectively through your stomach than through your nasal passages, so you need to take more to have the same effect.

Your GP or endocrinologist may suggest switching your treatment to tablets if you develop a cold that prevents you using the nasal spray.

Desmopressin is very safe to use and has few side effects.

But possible side effects can include:

• headache 
• stomach pain
• feeling sick
• a blocked or runny nose
• nosebleeds 

If you take too much desmopressin or drink too much fluid while taking it, it can cause your body to retain too much water.

This can result in:

• headaches
• dizziness
• feeling bloated
• hyponatraemia – a low level of sodium (salt) in your blood

Symptoms of hyponatraemia include:

• a severe or prolonged headache
• confusion
• nausea and vomiting

If you think you may have hyponatraemia, stop taking desmopressin immediately and call your GP for advice.

If this is not possible, go to your local A&E department.

Nephrogenic diabetes insipidus

If you have nephrogenic diabetes insipidus that's caused by taking a particular medication, such as lithium or tetracycline, your GP or endocrinologist may stop your treatment and suggest an alternative medication.

But do not stop taking it unless you have been advised to by a healthcare professional.

As nephrogenic diabetes insipidus is caused by your kidneys not responding to AVP, rather than a shortage of AVP, it usually cannot be treated with desmopressin.

But it's still important to drink plenty of water to avoid dehydration.

If your condition is mild, your GP or endocrinologist may suggest reducing the amount of salt and protein in your diet, which will help your kidneys produce less urine.

This may mean eating less salt and protein-rich food, such as processed foods, meat, eggs and nuts.

Do not alter your diet without first seeking medical advice.

Your GP or endocrinologist will be able to advise you about which foods to cut down on.

Find out more about eating a healthy, balanced diet.

If you have more severe nephrogenic diabetes insipidus, you may be prescribed a combination of thiazide diuretics and a non-steroidal anti-inflammatory drug (NSAID) to help reduce the amount of urine your kidneys produce. 

Thiazide diuretics

Thiazide diuretics can reduce the rate the kidney filters blood, which reduces the amount of urine passed from the body over time.

Side effects are uncommon, but include:

• dizziness when standing
• indigestion 
• very sensitive skin 
• erectile dysfunction (impotence) in men 

This last side effect is usually temporary and should resolve itself if you stop taking the medication.

Non-steroidal anti-inflammatory drugs (NSAIDs)

Non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, help reduce urine volume further when they're used in combination with thiazide diuretics.

But long-term use of NSAIDs increases your risk of developing a stomach ulcer.

To counter this increased risk, an additional medication called a proton pump inhibitor (PPI) may be prescribed.

PPIs help protect your stomach lining against the harmful effects of NSAIDs, reducing the risk of ulcers forming.

Find out more about treating stomach ulcers

Help with health costs

If you have diabetes insipidus, you do not have to pay prescription charges for desmopressin.

You'll need to fill in a medical exemption (MedEx) certificate to qualify.

See Help with health costs for more information about how to apply for a MedEx certificate.

You may have to pay for other drugs that may be required on a short-term basis, such as thiazide diuretics.

The 2 main complications of diabetes insipidus are dehydration and an electrolyte imbalance. Complications are more likely if the condition goes undiagnosed or is poorly controlled.

Dehydration

If you have diabetes insipidus, your body will find it difficult to retain enough water, even if you drink fluid constantly.

This can lead to dehydration, a severe lack of water in the body.

If you or someone you know has diabetes insipidus, it's important to look out for the signs and symptoms of dehydration.

These may include:

• dizziness or lightheadedness
• a headache
• a dry mouth and lips
• sunken features (particularly the eyes)
• confusion and irritability

Dehydration can be treated by rebalancing the level of water in your body.

If you're severely dehydrated, you may need intravenous fluid replacement in hospital.

This is where fluids are given directly through a drip into your vein.

Find out more about treating dehydration

Electrolyte imbalance

Diabetes insipidus can also cause an electrolyte imbalance.

Electrolytes are minerals in your blood that have a tiny electric charge, such as sodium, calcium, potassium, chlorine, magnesium and bicarbonate.

If the body loses too much water, the concentration of these electrolytes can go up simply because the amount of water they're contained in has gone down.

This dehydration disrupts other functions of the body, such as the way muscles work.

It can also lead to:

• a headache
• feeling tired all the time (fatigue)
• irritability
• muscle pain