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What is Diabetes Insipidus and why do we get it?

Diabetes insipidus (DI) is a disorder in which your kidneys are unable to retain water. This results in the production of large volumes of urine which in turn makes you feel dry and very thirsty. It is very important to point out that DI is not related to the type of diabetes most people have heard of, diabetes mellitus. In DI, there is no problem with the sugar in the blood or urine. The problem either concerns the lack of a water-retaining hormone or chemical in the blood (called Vasopressin; sometimes Anti-diuretic Hormone) or is sometimes due to an abnormality in the kidneys which prevents them from responding to this hormone. The hormone itself is normally secreted by the Pituitary gland, which is located at the base of the brain, just behind the bridge of the nose.

Most DI is caused by inadequate secretion of vasopressin by the pituitary gland. This can happen in varying degrees. Sometimes it occurs on its own, but in many cases it is accompanied by loss of other hormones made by the pituitary. In this event, it is most likely to be caused either by abnormalities of the pituitary gland or as a result of treatment to remove an enlarged pituitary gland. If you experience DI following pituitary surgery, this may well be temporary, in which case it will only last a week or two, but in some cases it may be permanent. DI can occur at any age, but is mostly found in adults, as pituitary enlargement is most common between the ages of 20 and 50. It is a rare disorder, affecting only about 1 in 25000 people.

The other form of DI, which occurs when the kidneys cannot respond to the vasopressin secreted by the pituitary gland, is very rare indeed. It is either caused by an inherited abnormality in the mechanism which recognises vasopressin in the kidney, or it can be caused by a number of diseases of the kidney itself.

What does it feel like to have DI?

If you suffer from DI, you may find you feel generally unwell for no very obvious reason. The main symptoms, however, are that you will feel extremely thirsty much of the time, no matter how much you drink, and that you will find you need to pass urine very frequently, even during the night. You may excrete as much as 4-5 gallons of urine a day. It is important that you do not try to prevent this by ignoring your thirst and drinking less, or you will disturb the balance of water in your body.

Coping with the stress of diabetes insipidus

In addition to physical issues, many people find pituitary illness emotionally traumatic. Particularly if you were unwell for some time before a correct diagnosis was made, there may be stress caused either by specific physical aspects or by factors such as change to body image, exhaustion, anxiety and so on. In addition, both the fear of anticipated surgery so close to the brain and the fact that, for some people recovery can take quite a while, can be stressful, particularly if it follows a long period of ill health leading up to the diagnosis. All these issues can be just as difficult for family and close friends as for the patients themselves. Your GP will be able to arrange counselling if this is required (see GP Factfile sheet 12). You may also find it useful to make contact with The Pituitary Foundation's support team in Bristol (telephone 0845 450 0375) and/or with your nearest local support group, where you will find many people keen to help and support you.

How is it diagnosed? What tests are carried out and how does it feel?

The method of diagnosis is simply to deprive you of fluid for 6-8 hours and see if there is a reduction in the volume of urine. You can expect to feel quite thirsty during this part of the test. The next stage is to give you a small quantity of vasopressin, usually as an injection. You will then stop passing urine. Once you are allowed to drink again, you will begin to feel better. If you need other hormone treatments, you will need to continue taking them during the test. This test can be performed in an outpatient clinic, but it does require attendance for a whole day.

How is DI treated?

If your DI is diagnosed as being caused by a lack of ADH (Vasopressin) production from the pituitary gland, it needs to be treated with a substance like vasopressin, which acts specifically on the kidneys. This compound only needs to be taken once or twice a day. It is called Desmopressin, but you will normally hear it referred to as DDAVP (nasal drops or tablets) or as Desmospray (nasal spray). It is usually administered by spray into the nose, where it is absorbed and carried into the blood stream. It has remarkably few side-effects and you should have no problems taking it unless you have a heavy cold. Desmopressin can be absorbed through the gut and can therefore be taken in tablet form. This requires a larger dose as only a rather small proportion is absorbed in this way, so tablets may need to be taken more than twice a day.

You will gradually feel better once you are taking desmopressin. Overall, the treatment of DI is very straightforward and you need have no worries about handling this aspect of your illness.

The only significant side-effect is excessive water retention due to taking too much desmopressin, which dilutes the blood and lowers the blood sodium concentration (Hyponatraemia).

Aftercare

It is possible that your condition will require long-term monitoring and this will be shared by your Endocrinologist and GP. Because pituitary conditions are relatively rare, you might find that you will be the only patient with DI your GP is treating and (s)he might find it helpful to have a copy of our Pituitary Disease Factfile for General Practitioners.

General information on lifestyle issues and useful addresses are also available on this web site.

This leaflet has been prepared for patients with diabetes insipidus. The aim of this page is to provide general information about DI and how it is treated. It is written in general terms, therefore, not all of it will apply to you. Hopefully you will find it helps you to understand your condition better and gives you a basis for discussion with your GP or endocrinologist.

We would like to emphasise that all patients are different and you should always seek advice from your specialist or GP.

This leaflet is published through an educational grant from Ferring Pharmaceuticals, manufacturers of DDAVP and Desmospray.

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