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Diabetes insipidus is very different from diabetes mellitus, which is often just referred to as diabetes. Diabetes mellitus is far more common and occurs when there is too much glucose (sugar) in the blood. It is possible for someone with diabetes mellitus to also develop diabetes insipidus, although this is extremely rare.
What is diabetes insipidus?
The amount of water in the body is regulated by a hormone which is known as antidiuretic hormone (ADH), or 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.
Types of diabetes insipidus
There are two types of diabetes insipidus:
- cranial diabetes insipidus - which occurs when there is a shortage of ADH in your body, and
- nephrogenic diabetes insipidus - which occurs when your kidneys do not respond properly to ADH.
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 type of diabetes insipidus is more common than nephrogenic diabetes insipidus, and can be caused by damage to the hypothalamus, or pituitary gland, such as through an infection, operation, or head injury.
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.
Diabetes insipidus can be treated by correcting the amount of urine that is produced by the body, although the condition usually requires life-long treatment.
Symptoms of diabetes insipidus
The two main symptoms of diabetes insipidus are:
- needing to pass large amounts of urine often, and
- feeling thirsty all the time.
These symptoms, and others that you may experience if you have diabetes inspidus, are outlined below.
Passing excess urine
If you have diabetes insipidus, you may find that you need to pass pale, watery urine as often as every 15-20 minutes. You may also produce as much as four to five gallons of urine every day.
Constantly needing to pass urine can make it difficult to be out and about without knowing where the nearest toilet is. If you have diabetes insipidus, the Pituitary Foundation (links to external site) can provide a toilet facility card, which will allow you to use toilets in non-public places, when there may not be a public facility available.
If you have diabetes insipidus, and you drink water all the time, you may find that you are still constantly thirsty. You may 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, you may find that your sleeping patterns and daily activities are disrupted as a result. This can cause tiredness, irritability, and difficulty concentrating, which can affect your day-to-day life even further.
Generally feeling unwell
If you have diabetes insipidus, you may find that you feel generally unwell and 'run down' much of the time for no apparent reason.
'Failure to thrive' in children
Although diabetes insipidus is more common in adults than it is in children, it is possible to develop the condition at any age. In babies, and young children, the symptoms of diabetes insipidus can result in a 'failure to thrive', where they grow at a slower rate than normal.
If your child has diabetes insipidus, as well as the main symptoms, you may find that they do not grow or gain weight at the normal rate. Your child may also be pale and lethargic (lacking in energy), and have dry skin. You may also find that your child tends to wet the bed frequently, or produces very wet nappies.
Risks of dehydration
The symptoms of diabetes insipidus can be difficult to deal with.
However, you should never try to ignore your thirst in order to pass less urine. Doing so can affect the balance of water in your body and lead to dehydration (a severe lack of water in your body).
Diabetes insipidus that is undiagnosed, or poorly controlled, can also cause dehydration. If too much water is lost from your body, the concentration of other substances, such as sodium (salt), can get dangerously high. Normally, salt helps to control the pressure and amount of fluid which passes between your blood and body tissues.
However, if there is too much salt in your body, it can cause you to become lethargic (lacking in energy) and confused. In severe cases, dehydration and high salt levels can cause fits, and eventually, a state of coma.
Causes of diabetes insipidus
Diabetes insipidis is caused by a hormone known as antidiuretic hormone (ADH). ADH is also sometimes called vasopressin.
ADH is produced by the hypothalamus, which is a gland in your brain that also controls processes in your body, such as mood and appetite. Until it is needed, ADH is stored in the pituitary gland, which is found just below your brain, behind the bridge of your nose.
The function of ADH is to regulate the levels of water in your body by controlling the amount of urine that your kidneys produce. When the levels of water in your body become low, your pituitary gland releases ADH in order to conserve water and stop the production of urine.
However, if you have diabetes insipidus, ADH fails to properly regulate your body's levels of water, and allows too much urine to be produced and passed from your body.
Cranial diabetes insipidus and nephrogenic diabetes insipidus can be caused in several different ways. These are outlined below.
Cranial diabetes insipidus - shortage of ADH
In some cases of cranial diabetes insipidus, it may not be possible to identify a cause.
However, if you have cranial diabetes insipidus, it is likely to be due to damage to your hypothalamus, or pituitary gland, resulting in a shortage of ADH. Damage to these areas prevents ADH from being properly produced, stored and released, and can be caused by:
- a tumour (cancerous or non-cancerous) in or around your hypothalamus, or pituitary gland,
- a head injury,
- an infection or illness affecting the brain, such as meningitis (infection of the meninges, the membranes in your brain), or
- surgery to the pituitary gland.
Cranial diabetes insipidus that is caused by a head injury, or surgery to your pituitary gland, can sometimes be temporary. If this is the case, your condition may only last for 1-2 weeks.
Nephrogenic diabetes insipidus - kidneys unresponsive to ADHA
As with cranial diabetes insipidus, it may not always be possible to find a cause for nephrogenic diabetes insipidus.
If you have nephrogenic diabetes insipidus, there is enough ADH in your body, but your kidneys do not respond to it and continue to produce too much urine.
Your kidneys contain tubules called nephrons, which control whether water is reabsorbed into your body, or passed as urine. Nephrogenic diabetes insipidus occurs when the nephrons in your kidneys fail to work properly, which can be caused by:
- an inherited kidney problem,
- kidney conditions, such as pyelonephritis (infection of your kidneys caused by bacteria), or
- certain medications, such as lithium and tetracycline, which can reduce the sensitivity of the nephrons. Lithium is sometimes prescribed to treat bipolar disorder (mood disorder with extreme mood swings), and tetracycline is an antibiotic that is sometimes used to treat common skin conditions, such as acne.
Diagnosing diabetes insipidus
See your GP if you think that you may have diabetes insipidus. They will ask you about your symptoms and carry out several tests. Your GP may refer you to an endocrinologist - a specialist in hormone conditions - for these tests.
As symptoms such as producing excess urine can be linked to other conditions, including diabetes mellitus, tests are needed in order to confirm, or rule out, a diagnosis of diabetes insipidus. The tests can also identify which of the two types of diabetes insipidus you have - cranial diabetes insipidus, or nephrogenic diabetes insipidus.
The tests that you may have to confirm a diagnosis of diabetes insipidus are described below.
Water deprivation test
If you have a water deprivation test, you will not be allowed to drink any liquid for several hours, to see whether or not you still continue to produce excess urine. If you have diabetes insipidus, you will continue to pass large amounts of dilute urine, compared with most people who would pass only a small amount of concentrated urine.
During the water deprivation test, your GP, or endocrinologist, will take urine samples in order to measure the amount of urine that you are producing. They may also carry out 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 (contain large amounts of water) with low levels of other substances. However, if there is a high amount of sugar in your urine, you may have diabetes mellitus, not diabetes insipidus.
Antidiuretic hormone (ADH) test
After the water deprivation test, your GP, or endocrinologist will give you a small dose of ADH, usually as an injection. This will show how your body reacts to the hormone, and can help to identify which type of diabetes insipidus you have.
If the dose of ADH causes you to stop producing urine, it is likely that 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 excess urine despite the dose of ADH, it suggests that there is already enough ADH in your body, but that 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 have to have an MRI scan if your GP or endocrinologist thinks that 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 will need to be treated before you can receive treatment for diabetes insipidus.
Treating diabetes insipidus
Treatment for diabetes insipidus aims to reduce the amount of urine that your body produces. Depending on the type of diabetes insipidus that you have, there are several ways of treating your condition and controlling your symptoms.
Treatment for 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 to be mild if you produce approximately three to four litres of urine over a 24-hour period.
If this is the case, you may be able to ease your symptoms simply by increasing the amount of water that you drink, in order to stay properly hydrated. 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 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 GP or endocrinologist may prescribe a treatment which takes the place of ADH, known as desmopressin.
Desmopressin is a manufactured version of ADH, and it is more powerful than the ADH that is naturally produced by your body. It works by acting as natural ADH should; by stopping your kidneys from producing urine when the level of water in your body is low.
Desmopressin is usually taken as a nasal spray called Desmospray, but you may also be prescribed desmopressin in the form of tablets, or nasal spray, known as DDAVP.
If you are prescribed Desmospray or DDAVP in the form of 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.
However, if you are prescribed DDAVP in the form of 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 DDAVP tablets if you develop a cold which prevents you from using the nasal spray.
Desmopressin is very safe to use and there are very few side effects. However, 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, and
- can lead to a dangerously low level of sodium (salt) in your blood (hyponatraemia).
Low salt levels can cause you to become drowsy and confused and, in severe cases, can result in fits, or a state of coma.
Therefore, you should never take more than your recommended dose of desmopressin, and while you are taking it, you should only drink fluids when you feel thirsty. You may also need to return to GP, or endocrinologist, for check-ups every 1-3 months, so that they can monitor your condition and the levels of salt in your blood.
Treatment for nephrogenic diabetes insipidus
If your nephrogenic diabetes insipidus is 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, you should not stop taking any medication unless you have been told to do so by a healthcare professional.
As nephrogenic diabetes insipidus is due to 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 ensure that you stay hydrated.
If your condition is mild, your GP or endocrinologist, may suggest changing your diet so that it is very low in salt and protein, which will help your kidneys produce less urine. This may mean eating less salt and protein rich foods, such as processed foods, meat, eggs and nuts. However, you should not alter your diet without medical advice; your GP 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 medication to help you reduce the amount of urine that your kidneys produce. This may be a diuretic known as hydrochlorothiazide, which is usually used to increase urine production. However, if you have nephrogenic diabetes insipidus, hydrochlorothiazide can work in the opposite way and help your kidneys to produce less urine.
Complications of diabetes insipidus
In some cases, diabetes insipidus can cause complications, particularly if it is undiagnosed, or poorly controlled.
If you have diabetes insipidus, your body finds it difficult to retain enough water, despite the fact that you may be drinking 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),
- dizziness, and
- 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 re-hydration fluid, rather than plain water because this will replace lost minerals, salts and sugars, as well as lost water.
However, if you are severely dehydrated, you may need treatment in hospital in which your fluids are replaced intravenously (through a drip into a vein).
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 to 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, leading to headache, fatigue, irritability and muscle pains.
An electrolyte imbalance can be treated in the same way as dehydration; with a re-hydration fluid containing replacement electrolytes.
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