Understanding Diabetes Insipidus
Diabetes Mellitus is of course well known although normally just referred to as 'diabetes'. However there is another kind of diabetes called 'diabetes insipidus', although rare, can cause all sorts of problems for people who suffer from it. The two forms of diabetes shouldn't be confused, they are different. With diabetes mellitus - type 1 and type 2 - there is too much glucose in the bloodstream. The word diabetes comes from the Greek language and is the verb for urinating (passing urine). The verb is used to describe both diabetes mellitus and diabetes insipidus as both affects the chemical composition of urine. However, the treatments for both these forms of diabetes are very different.
The basic definition for diabetes insipidus is given by NHS UK Patient Choices:
"Diabetes insipidus is a rare disorder where the system used by the body to
regulate its water levels becomes disrupted."
We'll have a closer look at this condition to see what actually happens and what areas of the body can be involved.
What causes diabetes insipidus?
In our bodies we have glands and hormones that regulate our water intake and elimination. The areas of the body and hormones mostly responsible for this are:
- The hypothalamus in the brain
- The pituitary gland in the brain
- ADH hormone - (anti-diuretic hormone also called vasopressin). A diuretic is a chemical or medicine that causes an increase in urine being eliminated by the body. Anti-diuretic hormone (ADH) regulates the fluid being lost from the body by preventing the kidneys from making too much urine.
How does ADH (anti-diuretic hormone) normally work?
ADH is made by the hypothalamus in the brain, then stored in the pituitary. This gland lies below the brain and just behind the bridge of the nose.
When the level of water in our body begins to get too low, then the pituitary gland releases the hormone ADH. This hormone will then prevent the kidneys from making urine so retaining water in the body.
With someone who has diabetes insipidus, ADH doesn't stop the production of urine by the kidney so excessive fluid is lost. There are two main ways this can happen:
- Cranial diabetes insipidus - in this type the body does not produce enough of the hormone ADH.
- Nephrogenic diabetes insipidus - in this type the body does produce enough ADH, but the kidneys don't respond to the hormone in the normal way.
There are a number of causes for diabetes insipidus. However, there are also people who develop the condition without any medical reason being apparent.
With cranial diabetes insipidus the most common known causes for the condition are:
- Severe head trauma - damage to the hypothalamus or pituitary gland.
- Surgical operation - complications may arise during brain surgery that perhaps damage part of the brain where the hypothalamus and/or pituitary gland is.
- Brain tumour - if the tumour happens to be in the region of the hypothalamus or the pituitary gland then diabetes insipidus may result.
- There are also cases where the cause is unknown. However, research is suggesting that the body's immune system may be attacking healthy brain tissue by mistake. Why this happens is not yet known.
- There are also other and rare medical conditions that may lead to diabetes insipidus developing such as meningitis, encephalitis and others.
Nephrogenic (nephro refers to the kidneys) diabetes insipidus is usually caused by:
- Congenital diabetes insipidus - basically the person was born with the condition. At the present time, according to NHS UK, two mutant genes have been identified for this form of diabetes.
- Acquired diabetes insipidus - the condition developed after birth and the causes are various. One of the most common causes of developing the condition is due to the drug lithium. This medication is widely used for the treatment of bipolar disorders. When people have used this drug over a long period of time, cells in the kidneys can be damaged and so they are not able to respond to the hormone ADH. When people have lithium stopped, the kidneys are often able to restore its normal functioning. However, some people do develop permanent kidney damage. Other conditions that cause damage to the kidney can also increase the risk of diabetes insipidus developing - for example kidney stones and kidney infections.
- There are also blood conditions such as hypercalcaemia - too much calcium in the blood - high levels cause kidney damage. Also hypokalaemia - this is where there is not enough potassium in the blood. Potassium is essential for all body cells, including the cells of the kidneys.
Now that we've looked at the causes, what are the symptoms of this condition?
Symptoms and treatment for diabetes insipidus
With diabetes insipidus the main symptoms people will describe are:
- Passing very large amounts of urine
- Very thirsty all the time
- Feeling unwell
- Daily life and sleep is disturbed
If it is a child that has diabetes insipidus then additional symptoms may be noticed such as:
- Being very irritable and crying frequently
- Unexplained weight loss and slowing of growth rate
- High body temperature
- When children are a little older they may have a loss of appetite, feel very lethargic and also experience bed wetting.
If there are any signs of these symptoms then you should speak to a doctor.
The main dangers of having untreated diabetes insipidus are:
Dehydration - this is of course a severe lack of fluid in the body. With diabetes insipidus this is caused by the extreme loss of fluid due to excessive urination. Even when drinking additional fluids, dehydration can still occur, so people need to ensure that they recognise the symptoms such as -
- headache, dizzy, dry mouth, dry lips, sunken face, when skin is pinched it remains standing, rather than springing back into shape. Confusion and irritability may also develop
- Electrolyte imbalance - when you are passing large amounts of fluid from the body, electrolytes are also lost. Electrolytes are chemicals that have a tiny electrical discharge and are essential for numerous body functions, as well as helping to balance fluid levels within the body. When you lose electrolytes from the body other essential functions can also be affected such as the muscles of the body - including areas like the heart. Examples of some electrolytes are: sodium, potassium, bicarbonate, chlorine, calcium, magnesium
The treatment for dehydration and electrolyte loss is the same - using rehydration fluid with electrolytes added.
Treatment for diabetes insipidus
The main aim of any treatment is to reduce the amount of urine passed. Because there is excessive fluid loss from the body, this is the main cause of other symptoms such as extreme and constant thirst and also dehydration.
In mild cases of diabetes insipidus simply drinking more fluid to replace what is lost is enough to control the condition. With more severe forms then ADH which is manufactured by chemists can be given. The nasal spray form of ADH is much more easily absorbed, but if this can't be used for some reason, then tablets can be used - although the ADH is not so easily absorbed by the stomach.
Interestingly, people who have diabetes insipidus can be successfully treated using a form of diuretic called 'thiazide diuretics'. Normally diuretics are used to get rid of excess fluid from the body, so make you pass urine more often. However, people who have diabetes insipidus, this medicine has the opposite effect, probably due to the fact that this drug makes the urine more concentrated, which then tends to stop it being passed. In addition, it has been found that when thiazide diuretics are combined with non-steroidal anti-inflammtory drugs, this reduces the urine output even more - the reason for this is unclear. However, many people who suffer from diabetes insipidus have had their symptoms greatly reduced by this combination.
Thankfully this distressing condition is still rare and research is continuing all the time to find out more about the causes and so develop better treatments. If you have any of the symptoms described in this article then you need to speak to your doctor as soon as possible.
This article is for information only and shouldn't be used as a substitute for professional medical advice.
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