Diabetes insipidus
Q: What is Diabetes Insipidus?
Diabetes Insipidus is caused when the pituitary gland (situated underneath the brain) has a problem producing the hormone vasopressin, also known as AVP, or when the action of AVP no longer works efficiently in the kidneys. This means that the body produces increased amounts of urine because the kidneys are unable to retain water.
It is important to point out that Diabetes Insipidus is not related to Diabetes Mellitus except that, when untreated, patients with either condition may have experience the symptoms of extreme thirst and the need to frequently pass urinate. In Diabetes Insipidus there is no problem with the level of glucose or insulin in the blood.
Q: What are the causes?
Diabetes Insipidus is much less common than Diabetes Mellitus. In many cases there is no obvious cause for the inability of the pituitary gland to make AVP (sometimes called Anti-diuretic Hormone or ADH). In other people an inflammation or infection around the pituitary gland, or a head injury may lead to the loss of AVP secretion. Operations on the pituitary gland may also lead to Diabetes Insipidus, but as in the case of a head injury, this is often temporary.
Q: How is it diagnosed?
There are several tests that can be done to diagnose Diabetes Insipidus. The first is a water deprivation test over 6–8 hours to see if there is a reduction in the volume of urine. The next stage would be to inject the person with a small amount of AVP which shows how well the kidneys respond to the hormone.
Diabetes Insipidus is usually treated with AVP or AVP-like substances such as demopressin (or DDAVP) which are self administered by the patient in the form of an injection, nasal drops, nasal spray or tablets and this returns the urine flow to normal. Treatment will usually be life-long, and in many cases may require hospital clinic attendance.
Although Diabetes Insipidus and Diabetes Mellitus are separate conditions, very rarely a patient with Diabetes Mellitus may also develop Diabetes Insipidus. It should be emphasised that this is very rare.
Q: Where can I get more information?
Diabetes UK is the largest charity devoted to the treatment and care of Diabetes Mellitus. There is a similar organisation for those who have Diabetes Insipidus called The Pituitary Foundation – The Foundation is a national support, information and advocacy organisation for pituitary patients, their families, friends and carers.
The Foundation operates throughout the UK and Republic of Ireland. Their contact details are as follows:
Pituitary Foundation
PO Box 1944
Bristol
BS99 2UB
Support and Information HelpLine: 0845 450 0375
Email: helpline@pituitary.org.uk
Website: www.pituitary.org.uk