Diabetes insipidus
The word diabetes is derived from Greek and means, “a syphoning of water through the body”. Insipidus is a Latin word meaning tasteless. The common form of diabetes which most people have heard about is Diabetes Mellitus; Mellitus means “sweet as honey”. Thus the name Diabetes Mellitus implies that patients with this condition lose large amounts of urine which is sweet and full of sugar, whereas in the case of Diabetes Insipidus the urine, although passed in excess, is tasteless and does not contain sugar.
Diabetes Insipidus is not related to Diabetes Mellitus except that patients with either condition are thirsty and pass a lot of urine. In the case of Diabetes Insipidus increased amounts of urine are passed because the body cannot retain water; the body has normal amounts of sugar and insulin. The inability to retain water is usually due to a shortage of a hormone called antidiuretic hormone (ADH, sometimes called vasopressin), which is made by the pituitary gland situated underneath the brain. Occasionally normal amounts of ADH are present, but the kidneys are not able to use it properly.
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 ADH. In other people an inflammation, infection around the pituitary gland or a head injury may lead to the loss of ADH 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.
Doctors diagnose Diabetes Insipidus by taking blood and urine samples from patients who have not had anything to drink for several hours. In most people this would lead to the passing of small amounts of concentrated urine, but patients with Diabetes Insipidus continue to pass large amounts of dilute urine. Special x-rays of the pituitary gland may also be performed.
Diabetes Insipidus treatment will usually be lifelong and in many cases may require hospital clinic attendance. The treatment is with ADH or ADH-like substances, which are self-administered by the person, in the form of a nasal spray and this returns the urine flow to normal.
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 unusual.
Diabetes UK is for people who have the condition Diabetes Mellitus. There is a national patient support group for pituitary patients, their families, friends and carers, which operates throughout the UK. This group is called The Pituitary Foundation.
Contact details:
The Pituitary Foundation
PO BOX 1944
Bristol
BS99 2UB
Tel: 0845 450 0375
Fax: 0845 450 0376
Email helpline@pituitary.org.uk
Website www.pituitary.org.uk