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Diabetes Insipidus in the Elderly

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Diabetes insipidus (DI) is a medical condition characterized by excessive thirst and passage of large volume of dilute urine. It should not be confused with diabetes mellitus (sugar diabetes) which is a condition of abnormally high blood glucose levels. There are mainly two types of diabetes insipidus depending upon the cause :

  • central DI due to a deficiency of antidiuretic hormone (ADH) which regulates water loss in the body, and
  • peripheral DI due to non responsiveness of kidney cells to ADH.

Treatment depends upon the cause of diabetes insipidus. Overall diabetes insipidus is not a common condition and does not have a predilection for older people. However, it is a consideration as it can sometimes arise with the chronic use of certain drugs particularly among seniors.

Symptoms of Diabetes Insispidus

Principal symptoms of diabetes insipidus include :

  • Excessive, uncontrollable thirst with typical craving for ice water.
  • Passage of large volume of dilute urine (daily urine production may reach 16 liters in contrast to 1.5 to 2.5 liters of daily urine production in normal healthy adults). This is seen as frequent urination.
  • Diarrhea, nausea and vomiting may sometimes be present.

Diabetes insipidus can lead to symptoms of dehydration due to fluid loss and an electrolyte imbalance. Symptoms of dehydration include dryness of mouth, sunken eyes, increased thirst, loss of skin elasticity, confusion and lethargy. There may also be  muscle weakness, muscle cramps and fatigue as a result of a loss of electrolytes. Increased water intake to combat increased thirst in diabetes inspidus patients may sometimes lead to symptoms of water intoxication.

Causes of Diabetes Insipidus

The kidney plays a pivotal role in maintaining body water electrolyte balance. Under the influence of anti diuretic hormone (ADH), the kdiney is able to control the amount of water lost in the urine. ADH is synthesized in the hypothalamus and stored in the pituitary gland, located at the base of the brain. In the hypothalamus there is thirst center (ventromedial nucleus) which regulates the thirst sensation.

If there is adequate water in body, the thirst center senses it and signals a decrease in the secretion of ADH from the hypothalamus. The lower levels of absence of ADH causes the kidney to reabsorb less water from the urine. Therefore dilute urine (more water in comparison to electrolytes) is produced an excreted. In the dehydrated state and with increased thirst, the hypothalamus is stimulated to increased production of ADH, which in turn influences the kidney to reabsorb water to produce concentrated urine (less water in comparison to electrolytes).

In central type of DI there is lack of ADH due to damage to pituitary or hypothalamus as a result of :

  • Surgery
  • Head trauma
  • Tumor
  • Meningitis

In peripheral type of DI, there is adequate ADH but kidney fails to respond to ADH due to :

  • Defective growth of kidney due to genetic abnormality.
  • Drug induced (lithium, amphotericin B, tetracycline)
  • Polycystic kidney disease

Dipsogenic diabetes insipidus is due to psychiatric disturbances like dementia which may lead to excessive thirst and abnormally high water intake with large volume urination as a consequence. In some cases of DI cause may never be found.

Treatment of Diabetes Insipidus

Treatment may vary between the different types of diabetes insipidus. In central DI, synthetic ADH (desmopressin) is used. In peripheral DI :

  • Low salt diet to reduce urine production.
  • Hydrochlorothiazide.

In drug-induced diabetes insipidus, discontinuing the causative drugs is adequate. It should only be undertaken under strict medical supervision.


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