About diabetes insipidus

What is diabetes insipidus?

What is the difference between diabetes insipidus and diabetes mellitus

Diabetes insipidus should not be confused with diabetes mellitus (DM), which results from insulin deficiency or resistance leading to high blood glucose, also called blood sugar. Diabetes insipidus and diabetes mellitus are unrelated, although they can have similar signs and symptoms, like excessive thirst and excessive urination.

Diabetes mellitus is far more common than diabetes insipidus and receives more news coverage. Diabetes mellitus has two main forms, type 1 diabetes and type 2 diabetes. Diabetes insipidus is a different form of illness altogether.

How is fluid in the body normally regulated?

The body has a complex system for balancing the volume and composition of body fluids. The kidneys remove extra body fluids from the bloodstream. These fluids are stored in the bladder as urine. If the fluid regulation system is working properly, the kidneys make less urine to conserve fluid when water intake is decreased or water is lost, for example, through sweating or diarrhea. The kidneys also make less urine at night when the body's metabolic processes are slower.


The hypothalamus makes antidiuretic hormone (ADH), which directs the kidneys to make less urine.

To keep the volume and composition of body fluids balanced, the rate of fluid intake is governed by thirst, and the rate of excretion is governed by the production of antidiuretic hormone (ADH), also called vasopressin. This hormone is made in the hypothalamus, a small gland located in the brain. ADH is stored in the nearby pituitary gland and released into the bloodstream when necessary. When ADH reaches the kidneys, it directs them to concentrate the urine by reabsorbing some of the filtered water to the bloodstream and therefore make less urine. Diabetes insipidus occurs when this precise system for regulating the kidneys' handling of fluids is disrupted.

What are the types of diabetes insipidus?

Central Diabetes Insipidus

The most common form of serious diabetes insipidus, central diabetes insipidus, results from damage to the pituitary gland, which disrupts the normal storage and release of ADH. Damage to the pituitary gland can be caused by different diseases as well as by head injuries, neurosurgery, or genetic disorders.

Nephrogenic Diabetes Insipidus

Nephrogenic diabetes insipidus results when the kidneys are unable to respond to ADH. The kidneys' ability to respond to ADH can be impaired by drugs-like lithium, for example-and by chronic disorders including polycystic kidney disease, sickle cell disease, kidney failure, partial blockage of the ureters, and inherited genetic disorders. Sometimes the cause of nephrogenic diabetes insipidus is never discovered.

Dipsogenic Diabetes insipidus

Dipsogenic diabetes insipidus is caused by a defect in or damage to the thirst mechanism, which is located in the hypothalamus. This defect results in an abnormal increase in thirst and fluid intake that suppresses ADH secretion and increases urine output. 

Gestational Diabetes Insipidus

Gestational diabetes insipidus occurs only during pregnancy and results when an enzyme made by the placenta destroys ADH in the mother. The placenta is the system of blood vessels and other tissue that develops with the fetus. The placenta allows exchange of nutrients and waste products between mother and fetus.



What are the symptoms for diabetes insipidus?

The most common signs and symptoms of diabetes insipidus are:

  • Extreme thirst
  • Excretion of an excessive amount of diluted urine

Depending on the severity of the condition, urine output can be as much as 16 quarts (about 15 liters) a day if you're drinking a lot of fluids. Normally, a healthy adult will urinate an average of less than 3 quarts (about 3 liters) a day.

Other signs may include needing to get up at night to urinate (nocturia) and bed-wetting.

Infants and young children who have diabetes insipidus may have the following signs and symptoms:

  • Unexplained fussiness or inconsolable crying
  • Trouble sleeping
  • Fever
  • Vomiting
  • Diarrhea
  • Delayed growth
  • Weight loss

When to see a doctor

See your doctor immediately if you notice the two most common signs of diabetes insipidus: excessive urination and extreme thirst.



What are the causes for diabetes insipidus?

Diabetes insipidus occurs when your body can't regulate how it handles fluids. Normally, your kidneys remove excess body fluids from your bloodstream. This fluid waste is temporarily stored in your bladder as urine, before you urinate.

When your fluid regulation system is working properly, your kidneys conserve fluid and make less urine when your body water is decreased, such as through perspiration.

The volume and composition of your body fluids remain balanced through a combination of oral intake and excretion by the kidneys. The rate of fluid intake is largely governed by thirst, although your habits can increase your intake far above the amount necessary. The rate of fluid excreted by your kidneys is greatly influenced by the production of anti-diuretic hormone (ADH), also known as vasopressin.

Your body makes ADH in the hypothalamus and stores the hormone in your pituitary gland, a small gland located in the base of your brain. ADH is released into your bloodstream when your body starts to become dehydrated. ADH then concentrates the urine by triggering the kidney tubules to release water back into your bloodstream rather than excreting as much water into your urine.

The way in which your system is disrupted determines which form of diabetes insipidus you have:

  • Central diabetes insipidus. The cause of central diabetes insipidus in adults is usually damage to the pituitary gland or hypothalamus. This damage disrupts the normal production, storage and release of ADH.

    The damage is commonly due to surgery, a tumor, an illness (such as meningitis), inflammation or a head injury. For children, the cause may be an inherited genetic disorder. In some cases the cause is unknown.

  • Nephrogenic diabetes insipidus. Nephrogenic diabetes insipidus occurs when there's a defect in the kidney tubules — the structures in your kidneys that cause water to be excreted or reabsorbed. This defect makes your kidneys unable to properly respond to ADH.

    The defect may be due to an inherited (genetic) disorder or a chronic kidney disorder. Certain drugs, such as lithium or the antiviral medications cidofovir and foscarnet (Foscavir), also can cause nephrogenic diabetes insipidus.

  • Gestational diabetes insipidus. Gestational diabetes insipidus is rare and occurs only during pregnancy and when an enzyme made by the placenta — the system of blood vessels and other tissue that allows the exchange of nutrients and waste products between a mother and her baby — destroys ADH in the mother.

  • Primary polydipsia. This condition — also known as dipsogenic diabetes insipidus or psychogenic polydipsia — can cause excretion of large volumes of dilute urine. Rather than a problem with ADH production or damage, the underlying cause is intake of excessive fluids.

    Prolonged excessive water intake by itself can damage the kidneys and suppress ADH, making your body unable to concentrate urine. Primary polydipsia can be the result of abnormal thirst caused by damage to the thirst-regulating mechanism, situated in the hypothalamus. Primary polydipsia has also been linked to mental illness.

In some cases of diabetes insipidus, doctors never determine a cause.



What are the treatments for diabetes insipidus?

Central Diabetes Insipidus

To treat the ADH deficiency that results from any kind of damage to the hypothalamus or pituitary, a synthetic hormone called desmopressin can be taken by an injection, a nasal spray, or a pill. While taking desmopressin, a person should drink fluids only when thirsty and not at other times. The drug prevents water excretion, and water can build up now that the kidneys are making less urine and are less responsive to changes in body fluids.

Nephrogenic Diabetes Insipidus

Desmopressin will not work for this form of diabetes insipidus. Instead, a person with nephrogenic diabetes insipidus may be given hydrochlorothiazide (HCTZ) or indomethacin. HCTZ is sometimes combined with another drug called amiloride. The combination of HCTZ and amiloride is sold under the brand name Moduretic. Again, with this combination of drugs, one should drink fluids only when thirsty and not at other times.

Dipsogenic Diabetes insipidus

Desmopressin or other drugs should not be used to treat dipsogenic diabetes insipidus because they may decrease urine output but not thirst and fluid intake. This fluid overload can lead to water intoxication, a condition that lowers the concentration of sodium in the blood and can seriously damage the brain. Scientists have not yet found an effective treatment for dipsogenic diabetes insipidus.

Gestational Diabetes Insipidus

Most cases of gestational diabetes insipidus can be treated with desmopressin. In rare cases, however, an abnormality in the thirst mechanism causes gestational diabetes insipidus, and desmopressin should not be used.

 



What are the risk factors for diabetes insipidus?

Nephrogenic diabetes insipidus that's present at or shortly after birth usually has a genetic cause that permanently alters the kidneys' ability to concentrate the urine. Nephrogenic diabetes insipidus usually affects males, though women can pass the gene on to their children.



Is there a cure/medications for diabetes insipidus?

There is currently no cure for diabetes insipidus, but certain treatments can be done to relieve your thirst and decrease the urge to urinate. There are four forms of this disorder:

  • Central diabetes insipidus
  • Nephrogenic diabetes insipidus
  • Gestational diabetes insipidus
  • Primary polydipsia
  • Hormone therapy
  • Low-salt diet
  • Drink more water
  • Desmopressin
  • Chlorpropamide
  • Hydrochlorothiazide (for nephrogenic diabetes insipidus)

These are some of the treatments and medications for preventing diabetes insipidus from affecting your daily life.



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