In normal “production” of urine, kidneys first filter the water, salt and other substances from the blood, and then reabsorbe part of the salt and most of the water from this fluid. The rest is concentrated urine that is excreted from the body. Reabsorbed water and salt are returining into the blood, thus maintaining the correct concentration of the blood and body fluids. Kidneys reabsorption of water from the urine stimulates antidiuretic hormone (ADH) which is excreted by rear lobe of the pituitary gland. In diseases known as diabetes insipidus, there is a lack of the hormone ADH, so the body excretes large amounts of diluted (aqueous) urine.
The most common cause of this disease is damage to the pituitary gland caused by severe head injury. In some cases, the disease can be the result of surgery on the pituitary gland, or radiotherapy of the pituitary gland or the surrounding area. Additional possible cause is the pressure on pituitary gland by pituitary tumor. However, sometimes in spite of the tests and trials, the cause remains unknown.
Diabetes insipidus should not to be confused with diabetes mellitus – i.e. with diabetes.
The patient ejects large amounts of colorless urine – up to 20 liters every 24 hours. This significant loss of fluid causes unquenchable thirst; patient on both day and night constantly feel the need to urinate and to drink. In other symptoms, which are also a consequence of unusually frequent urge to urinate, we include dry hands and constipation.
What to do?
As soon as symptoms occur, consult your doctor who will send you to the hospital for so-called urine concentration test. During the test you will not receive any liquid, and the volume of water in the urine is measured repeatedly. In normal person, who is deprived of water for several hours, ADH stimulates the kidneys to the reabsorption of water from urine in order to conserve water in the body; if the volume of water in your urine stays high, it means you have too little ADH hormones. The diagnosis will be confirmed by the action of injections of artificial ADH to urinate.
Drink as much water as you need. In some cases, when the patient does not urinates much, it may be enough to limit the intake of salt in the diet and taking diuretics, because these measures will achieve conservation of water in the kidneys. If the cause of the disease is pituitary tumor, it must be removed. In many cases, the disease is most successfully treated by an artificial form of ADH hormone, so-called desmopressin, which is taken in the form of nasal drops.
At the beginning of treatment, you will need to go to the doctor every day for the first 7-14 days to determine the correct dose. After that, drops are taken twice a day. The duration of this treatment depends largely on the cause of the disease. If the disease is a consequence of a head injury, surgery or radiotherapy, the affected gland (pituitary) can often recover for about a year, and the patient is fully healed. Otherwise, and for other reasons, you will need to take artificial ADH or diuretics for the rest of your life.