Definition and Overview

Diabetes insipidus (DI) is a rare disorder. It makes a person urinate more frequently and in larger amounts. Some patients can produce as much as 15 litres of urine per day. This is up to five times more than the normal amount. Because of this, patients feel thirsty all the time no matter how much water they drink and how often.

The disorder occurs due to a problem in the hypothalamus. The hypothalamus is the part of the brain that helps produce a number of hormones. One of them is the antidiuretic hormone (ADH).

ADH regulates and balances the amount of water in the blood. It tells the kidneys how much water to conserve based on a person’s water intake and level of activity. For example, if a person is running a marathon and sweating a lot, ADH will instruct the kidney to save water and make the urine more concentrated. This helps ensure that the patient will not become dehydrated.

There are two possible scenarios in which DI can occur. The first is when the hypothalamus is not making enough ADH. The second is when the kidneys are not responding to the ADH the way they should.

The disorder does not affect kidney function. This means that people who have it do not have to worry about needing dialysis in the future. Despite the disorder, the kidneys can still filter the blood and remove wastes and excess water that the body does not need.

Causes of Condition

DI has four different types. Each has a different cause. These include:

  • Central DI - This type occurs when the amount of ADH in the body is not enough. This happens when the hypothalamus is damaged due to a tumour, brain surgery, or a head injury.

  • Nephrogenic DI - This type occurs when the kidney tubules do not respond well to ADH. As a result, they do not reabsorb filtered water back into the body the way they should. This type can be hereditary. In other cases, it can be caused by certain medications and kidney diseases.

  • Gestational DI - In rare cases, the disorder can occur in pregnant women. This can happen when the placenta (which provides the foetus the nutrients it needs while inside the womb) releases an enzyme that damages the ADH. This form does not require treatment. It resolves a couple of weeks after childbirth.

  • Dipsogenic DI - This type occurs when a person drinks way more water than his or her body needs. This is often seen in people with mental problems. Too much water in the body reduces a person’s supply of ADH. This can cause the body to retain more fluid. This type does not require any form of treatment. It resolves on its own once the person stops drinking too much water.

Key Symptoms

Patients with the disorder need to pee all the time. They usually go to the bathroom every hour. This happens throughout the night and day. They also get thirsty no matter how much water they drink and they can wet the bed. Young children, on the other hand, find it difficult to sleep. They also usually suffer from fever and delayed growth.

The disorder can cause a number of complications. The most common is dehydration. Patients who are severely dehydrated have a dry mouth and skin as well as low blood pressure and constant headaches. They also experience fever and a fast heart rate.

Who to See and Types of Treatments Available

Patients showing signs of DI are advised to take the water deprivation test. For this test, they are not allowed to drink water until they become dehydrated. Urine and blood samples are then taken for lab testing. Through this, the doctor can determine the concentration of their blood and urine as well as measure the levels of ADH and minerals in their blood.

The test should only be performed by a specialist. This is a must especially if the patient is a child or pregnant woman. The specialist has to closely monitor the patient until the test is done. They have to make sure that the patient does not lose more than 5% of his or her body weight during the test. Otherwise, the patient can become dehydrated. When this happens, the patient may develop complications or even serious medical problems.

DI is not always a cause for concern. It is not known to cause severe symptoms in people with easy access to water. But going to the bathroom every hour can be very inconvenient for many.

Meanwhile, patients can face serious problems if they cannot replace the fluid they lose fast enough. This can be an issue in very young children who cannot tell adults about their symptoms. This can also happen in older people who have mental disorders.

Treatment options range from making simple diet changes to taking synthetic hormones for those who lack ADH. If the condition occurs because the kidneys do not respond well to ADH, patients are advised to reduce the amount of salt they eat. They are also given medications to reduce the amount of their urine. Those with dipsogenic DI, on the other hand, can make their symptoms go away by simply drinking less water.

References:

  • Ferri FF. Diabetes insipidus. In: Ferri’s Clinical Advisor 2016. Philadelphia, Pa.: Mosby Elsevier; 2016. https://www.clinicalkey.com.

  • Nephrogenic Diabetes Insipidus Foundation: “NDI Facts and Statistics.”

  • Diabetes Insipidus Foundation: “What Is Diabetes Insipidus?”

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