What is diabetes insipidus?
Diabetes insipidus is a rare disorder where the system used by the body to regulate its water levels becomes disrupted.
This disruption leads to the main symptoms of diabetes insipidus:
- excessive and prolonged thirst
- needing to urinate frequently
- passing large amounts of urine – in the most severe cases a person can pass up to 20 litres a day
Read more about the symptoms of diabetes insipidus.
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 liquid in the body.
ADH is made by a part of the brain called the hypothalamus and is stored just below the brain, in the pituitary gland, until 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 producing urine.
In cases of diabetes insipidus, ADH does not stop the kidneys from producing urine and allows too much water to be passed from the body.
Read more about the causes of diabetes insipidus.
Types of diabetes insipidus
There are two main types of diabetes insipidus:
Cranial diabetes insipidus
Cranial diabetes insipidus occurs when there is not enough ADH in the body to regulate the production of urine.
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, brain tumour or head injury.
However, in around one in three cases of cranial diabetes insipidus there is no obvious reason why the hypothalamus stops making enough ADH.
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 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.
Very rarely the genes a person inherits can trigger nephrogenic diabetes insipidus.
Treating diabetes insipidus
In mild cases of cranial diabetes insipidus treatment may not be required as long as a person compensates for excessive urination by drinking more water.
However, a medication called desmopressin can be used to replicate the functions of ADH if necessary.
Nephrogenic diabetes insipidus is often treated with medications called thiazide diuretics which reduce the amount of urine the kidneys produce.
Read more about the treating diabetes insipidus.
The levels of fluids inside the body could potentially drop to a dangerously low level, which is known as dehydration.
Mild dehydration can be treated with rehydration solutions which replace fluid, as well as lost minerals, salts and sugars. Severe dehydration is treated in hospital.
Read more about the complications of diabetes insipidus.
Who is affected
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 and ethnic backgrounds. Both sexes are equally affected.
Symptoms of diabetes insipidus
The two main symptoms of diabetes insipidus are:
- needing to pass large amounts of urine often
- feeling thirsty all the time
These and other symptoms you may experience if you have diabetes insipidus are outlined below.
Passing excess urine
You may pass pale, watery urine as often as 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.
You may be constantly thirsty and have a 'dry' feeling that is always present, no matter how much water you drink.
Trouble sleeping and carrying out daily activities
If you need to pass urine often and always feel thirsty, your sleeping patterns and daily activities may be disrupted as a result. This can cause [tiredness], irritability and difficulty concentrating, which can affect your daily life further.
Generally feeling unwell
If you have diabetes insipidus, you may feel generally unwell and 'run down' much of the time for no apparent reason.
Additional symptoms in children
In very young children who are unable to speak, it may be difficult to realise they are excessively thirsty. Signs and symptoms that could suggest diabetes insipidus include:
- excessive crying
- slower than expected growth
- hyperthermia (high body temperature)
- unexplained weight loss
In older children symptoms of diabetes insipidus include:
- wetting the bed
- loss of appetite
- fatigue (feeling tired all the time)
When to seek medical advice
You should always contact your doctor for advice if you find yourself feeling thirsty all the time. While it may not necessarily be the result of diabetes insipidus, it should be investigated.
You should also see your doctor if you are passing more urine than normal. Most healthy adults will pass urine no more than 4-7 times in a 24 hour period.
Children tend to urinate more frequently as they have smaller bladders, but if your child urinates more than 10 times a day they may require further investigation by your doctor.
Diabetes insipidus causes
Diabetes insipidus is related to a chemical produced by the body known as antidiuretic hormone (ADH). ADH is sometimes called vasopressin.
ADH is produced by the hypothalamus, a section in your brain that also controls mood and appetite. Until needed, ADH is stored in the pituitary gland, found below your brain, behind the bridge of your nose.
The function of ADH is to regulate the level of water in your body by controlling the amount of urine your kidneys produce. When the level of water in your body drops, your pituitary gland releases ADH to conserve water and stop the production of urine.
However, if you have 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 does not 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 fail to respond to the ADH in the normal way.
Possible underlying causes for both types of diabetes insipidus are described below.
Causes of 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 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
In about a third of cases, no apparent cause can be found for the development of the condition. These types of cases, known as idiopathic cases, appear to be related to the immune system attacking healthy brain tissue by mistake. What causes the immune system to do this is unclear.
Less common causes of cranial diabetic insipidus include:
- cancers that spread from another part of the body to the brain
- Wolfram syndrome, a rare genetic disorder that also causes sight and 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
Causes of nephrogenic diabetes insipidus
Your kidneys contain nephrons, which 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. This does not occur in cases of nephrogenic diabetes insipidus, leading to excessive thirst and excessive urine production.
The possible causes of nephrogenic diabetes insipidus are classed as either:
- congenital, which means the condition is present at birth
- acquired, which means the condition develops later in life due to an external factor
Congenital nephrogenic diabetes insipidus
Two genetic mutations (abnormal changes to the genes) have been identified that cause nephrogenic diabetes insipidus present at birth.
The first is known as the AVRP2 gene mutation and is responsible for 90% of all cases of congenital diabetes insipidus (although it is still very rare, occurring in an estimated 1 in 250,000 births). This gene mutation can only be passed down by mothers (who are not 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.
Read more about genetics.
Acquired nephrogenic diabetes insipidus
The most common cause of acquired nephrogenic diabetes insipidus is the medication lithium.
Lithium is widely used to treat bipolar disorder. Long-term use of lithium can damage the cells of the kidneys, meaning 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 treatment with lithium will often restore normal kidney function, though in many cases damage to the kidneys is permanent.
Due to these risks, it is recommended that you have kidney function tests every three months if you are taking lithium.
Read more about the treatment of bipolar disorder.
Other causes of acquired nephrogenic diabetes insipidus include:
- hypercalcaemia, a condition where there is too much calcium in the blood (high calcium levels can damage the kidneys)
- hypokalemia, a condition where there is not enough potassium in the blood (all the cells in the body, including kidney cells, require potassium to function properly)
- the kidneys being damaged by infection (the medical term for kidney infection is pyelonephritis)
- ureteral obstruction, when one or both of the tubes that connect the kidneys to the bladder (the ureters) become blocked by an object such as a kidney stone, which can then damage the kidneys
Diagnosing diabetes insipidus
See your doctor if you think you have diabetes insipidus. They will ask about your symptoms and carry out several tests. Your doctor may refer you to a specialist in hormone conditions (an endocrinologist) for these tests.
The tests can also identify which type of diabetes insipidus 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 will 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 are producing is 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 blood sugar (glucose), calcium and potassium. If you have diabetes insipidus, your urine will be very diluted, with low levels of other substances. However, a high amount of sugar in your urine may be a sign of type 1 or type 2 diabetes, not 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 shows how your body reacts to the hormone which helps identify the type of diabetes insipidus you have.
If the dose of ADH stops you producing urine, it is likely your condition is due to a shortage of ADH. If this is the case, you may be diagnosed with cranial diabetes insipidus.
However, if you continue to produce urine, despite the dose of ADH, it suggests there is already enough ADH in your body, but your kidneys are not responding to it. In this case, you may be diagnosed with nephrogenic diabetes insipidus.
Magnetic resonance imaging (MRI) is a scan that uses a strong magnetic field and radio waves to produce images of the inside of your body, including your brain.
You may need an MRI scan if your doctor or 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.
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.
Treating cranial diabetes insipidus
If you have mild cranial diabetes insipidus, you may not need any medical treatment for your condition.
Cranial diabetes insipidus is considered mild if you produce approximately three to four 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 doctor 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 your cranial diabetes insipidus is more severe, drinking water may not be enough to keep your symptoms under control. As your condition is due to a shortage of antidiuretic hormone (ADH), your doctor or endocrinologist may prescribe a treatment that takes the place of ADH, known as desmopressin.
Desmopressin is a manufactured version of ADH, and is 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 are prescribed desmopressin as a nasal spray, you will need to spray it inside your nose once or twice a day, where it is quickly absorbed into your bloodstream.
If you are 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 doctor 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. There are few side effects, but they can include:
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:
- feeling bloated
- hyponatraemia (a dangerously low level of sodium (salt) in your blood)
Symptoms of hyponatraemia include:
- an unusually bad or prolonged headache
- unexplained weight gain
- nausea (feeling sick)
- vomiting (being sick)
If you think you may have hyponatraemia, immediately stop taking the medication and call your doctor for advice. If this is not possible, go to your local accident and emergency (A&E) department.
Thiazide diuretics are a type of medication normally used to increase the flow of urine from the body, so their use may seem counterproductive in the treatment of diabetes insipidus.
However, they have the useful side effect of making the urine more concentrated (so it contains a high level of waste products).
For people with diabetes insipidus, the medication has a completely opposite effect to that which is normally expected. 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
- skin becoming very sensitive
- in men, erectile dysfunction (impotence)
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 still unclear, when used in combination with thiazide diuretics, the class of painkillers called non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, help reduce urine volume further.
However, long-term use of NSAIDs increases your risk of developing a stomach ulcer. To counter this increased risk you may be prescribed an additional medication called a proton pump inhibitor (PPI). PPIs can help protect the lining of your stomach against the harmful effects of NSAIDs; reducing the risk of any ulcers forming.
Read more about the treatment of stomach ulcers.
Treating nephrogenic diabetes insipidus
If your nephrogenic diabetes insipidus is caused by taking a particular medication, such as lithium or tetracycline, your doctor or endocrinologist may stop your treatment and suggest an alternative medication. Do not stop taking any medication unless you have been told to do so by a healthcare professional.
As nephrogenic diabetes insipidus results from your kidneys not responding to ADH, rather than a shortage of ADH, it cannot be treated with desmopressin. However, it is still important to drink plenty of water to avoid dehydration.
If your condition is mild, your doctor or endocrinologist may suggest changing your diet so it is very low in salt and protein, which will help your kidneys produce less urine. This may mean eating less salt and less protein-rich food, such as processed foods, meat, eggs and nuts. Do not alter your diet without medical advice. Your doctor or endocrinologist can advise you about which foods to cut down on.
If your nephrogenic diabetes insipidus is more severe, you may be prescribed a combination of thiazide diuretics and an NSAID to help reduce the amount of urine your kidneys produce.
Complications of diabetes insipidus
In some cases, diabetes insipidus can cause complications, particularly if undiagnosed or poorly controlled.
If you have diabetes insipidus, your body finds it difficult to retain enough water, even if you drink fluid constantly. This can lead to dehydration, which is a severe lack of water in your body.
If you or someone you know has diabetes insipidus, it is important to look out for the signs and symptoms of dehydration, which may include:
- 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 are very dehydrated, it is better to drink a rehydration fluid rather than plain water, as this will replace lost minerals, salts and sugars as well as lost water.
If you are severely dehydrated, you may need treatment in hospital, where your fluids are replaced intravenously (through a drip into a vein).
Read more about the treatment of dehydration.
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. Along with antidiuretic hormone (ADH), electrolytes help maintain the balance of water in your body.
If you have diabetes insipidus, these electrolytes can become unbalanced and the amount of water in your body is affected. This can cause dehydration and disrupt other body functions, such as the way muscles work, which can lead to headache, fatigue (feeling tired all the time), irritability and muscle pain.
An electrolyte imbalance can be treated in the same way as dehydration, with a rehydration fluid containing replacement electrolytes.