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Diabetes insipidus

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Diabetes insipidus



Introduction 

Diabetes insipidus is a rare condition where you produce a large amount of urine and often feel thirsty.

Diabetes insipidus isn't related to diabetes mellitus (usually just known as diabetes), but it does share some of the same signs and symptoms.

The two main symptoms of diabetes insipidus are:



thirst (polydipsia)



passing large amounts of urine even at night (polyuria)



In very severe cases of diabetes insipidus, up to 20 litres of urine can be passed in a day.

When to seek medical advice

You should always go to 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.

Children tend to urinate more frequently 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 determine what's causing the problem.

What causes diabetes insipidus?

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

ADH plays a key role in regulating the amount of fluid in the body. It's produced by specialist nerve cells in a part of the brain known as the hypothalamus. ADH passes from the hypothalamus to the pituitary gland where it's stored until needed.

The pituitary gland releases ADH 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, making the kidney produce urine that's more concentrated.

In diabetes insipidus, the lack of production of ADH or, in rare cases, the kidney not responding to ADH, means the kidney can't make enough concentrated urine and too much water is passed from the body.

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

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's not enough ADH in the body to regulate urine production.

Cranial diabetes insipidus is the most common type of diabetes insipidus. It can be caused by damage to the hypothalamus or pituitary gland – for example, after an infection, operation, brain tumour or head injury.

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

Nephrogenic diabetes insipidus

Nephrogenic diabetes insipidus occurs when there's enough ADH in the body but the kidneys fail to respond to it. It can be caused by kidney damage or, in some cases, inherited as a problem on its own.

Some medications, particularly lithium (used to treat serious mental health conditions, such as bipolar disorder), can cause nephrogenic diabetes insipidus.

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 ADH.

Nephrogenic diabetes insipidus is often treated with medications called thiazide diuretics which reduce the amount of urine the kidneys produce.

Complications

As diabetes insipidus causes excessive urination, the amount of water in the body can become low. This is known as dehydration.

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



 


 


Diabetes insipidus makes you feel thirsty all the time due to the need to urinate frequently 


Who's affected by diabetes insipidus?

Diabetes insipidus is a rare condition that affects about one in 25,000 people in the general population.

People of all ages and ethnicities can develop the condition and both sexes are affected equally.

 

Symptoms of diabetes insipidus 

Needing to frequently pass large amounts of urine and feeling thirsty are the two main symptoms of diabetes insipidus.

If you have diabetes insipidus, you may pass pale, watery urine every 15-20 minutes. The amount of urine passed can range from 3 litres (5.2 pints) in mild cases to up to 20 litres (35 pints) 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 pass urine regularly and always feel thirsty, your sleeping patterns and daily activities may be disrupted. This can causetiredness, 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



hyperthermia (high body temperature)



unexplained weight loss



In older children, symptoms of diabetes insipidus include:



wetting the bed (enuresis)



loss of appetite



feeling tired all the time (fatigue)



Toilet card

Frequently needing to pass urine can make being out in public difficult, particularly if you don't know where the nearest toilet is.

The Bladder and Bowel Foundation (B&BF) has produced a 'Just Can't Wait' toilet card that can be used to help you gain access to toilets when you're out and about.

The card states that the holder has a medical condition and needs to use a toilet quickly. It also has a universally acknowledged image for a toilet, which is particularly useful for people who don't speak English as their first language.

Causes of diabetes insipidus 

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

ADH is produced by the hypothalamus and it's 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.

ADH 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 ADH to conserve water and stop the production of urine.

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

In cranial diabetes insipidus, the body doesn't produce enough ADH, so excessive amounts of water are lost during urination.

In nephrogenic diabetes insipidus, ADH is produced at the right levels but, for a variety of possible reasons, the kidneys don't respond to it in the normal way.

Possible underlying causes for both types of diabetes insipidus are described below.

Cranial diabetes insipidus

The three most common causes of cranial diabetes insipidus are:



a brain tumour that damages the hypothalamus or pituitary gland – this accounts for around one in four cases



a severe head injury that damages the hypothalamus or pituitary gland – this accounts for around one in six cases



complications that occur during brain surgery – this accounts for one in five cases



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 healthy brain tissue by mistake. It's unclear what causes the immune system to do this.

Less common causes of cranial diabetic insipidus include:



cancers that spread from another part of the body to the brain



Wolfram syndrome, which is 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 control how much water is reabsorbed into your body and how much is passed as urine.

In a healthy person, ADH signals to the nephrons to reabsorb water into the body. In nephrogenic diabetes insipidus this doesn't occur, leading to excessive thirst and urine production.

Nephrogenic diabetes insipidus can be congenital (present at birth) or acquired (where it develops later in life as a result of an external factor). These are described in more detail below.

Congenital nephrogenic diabetes insipidus

Two genetic mutations (abnormal gene changes) 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. However, it's still rare, occurring in an estimated one 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.

Acquired nephrogenic diabetes insipidus

Lithium is the most common cause of acquired nephrogenic diabetes insipidus. It's a medication that's often used to treat bipolar disorder. Long-term lithium use can damage the cells of the kidneys so that they no longer respond to ADH.

Just over half of all people on long-term lithium therapy will develop some degree of nephrogenic diabetes insipidus. Stopping lithium treatment will often restore normal kidney function, although in many cases the damage to the kidneys is permanent.

Due to these risks, it's recommended that you have kidney function tests every three months if you're taking lithium.

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 isn't 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 one or both tubes (ureters) that connect the kidneys to the bladder become blocked by an object, such as a kidney stone, which damages the kidneys



Diagnosing diabetes insipidus 

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 type1 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 pass large amounts of dilute urine, when normally you would only pass 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.

Antidiuretic hormone (ADH) test

After the water deprivation test, you may be given a small dose of ADH, usually as an injection. This will show how your body reacts to the hormone, which will help identify the type of diabetes insipidus you have.

If the dose of ADH stops you producing urine, it's likely your condition is due to a shortage of ADH. If this is the case, you may be diagnosed with cranial diabetes insipidus.

However, continuing to produce urine despite the dose of ADH suggests that there's already enough ADH in your body, but your kidneys aren't responding to it. In this case, you may be diagnosed with nephrogenic diabetes insipidus.

MRI scan

Magnetic resonance imaging (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 due to an abnormality in your hypothalamus or pituitary gland, such as a tumour, it may need to be treated before you can receive treatment for diabetes insipidus.

 

Treating 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 3-4 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 (specialist in hormone conditions) may advise you to drink a certain amount of water every day, usually at least 2.5 litres.

However, if you have more severe cranial diabetes insipidus, drinking water may not be enough to control your symptoms. As your condition is due to a shortage of antidiuretic hormone (ADH), your GP or endocrinologist may prescribe a treatment that takes the place of ADH, known as desmopressin (see below).

Desmopressin

Desmopressin is a manufactured version of ADH that's more powerful than the ADH naturally produced by your body. It works just like natural ADH, stopping your kidneys producing urine when the level of water in your body is low.

Desmopressin can be taken as a nasal spray or in tablet form. 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 from using the nasal spray.

Desmopressin is very safe to use and has few side effects. However, possible side effects can include:



headache



stomach pain



feeling sick



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 dangerously 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 isn't possible, go to your local accident and emergency (A&E) department.

Thiazide diuretics

Thiazide diuretics are a type of medication that makes the urine more concentrated, so that it contains a high level of waste products.

By increasing the concentration of the urine, the medication reduces the amount of urine passed from the body.

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)

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

However, long-term use of NSAIDs increases your risk of developing astomach 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..

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. However, don't stop taking it unless you've been advised to by a healthcare professional.

As nephrogenic diabetes insipidus is caused by your kidneys not responding to ADH, rather than a shortage of ADH, it can't be treated with desmopressin. However, 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. Don't 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.

If you have more severe nephrogenic diabetes insipidus, you may be prescribed a combination of thiazide diuretics and an NSAID to help reduce the amount of urine your kidneys produce. 

 


Help with health costs

If you have diabetes insipidus, you're entitled to medical exemption (MedEx) certificates. This means you don't have to pay prescription charges for medication that you need to treat your condition.

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

Complications of diabetes insipidus 

Diabetes insipidus can sometimes cause complications, particularly if it's undiagnosed or poorly controlled.

Dehydration and an electrolyte imbalance are two of the main complications (see below).

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 light-headedness



headache



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.

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 headache, fatigue (feeling tired all the time), irritability and muscle pain.





Diabetes insipidus