An Overview of Polydipsia

A Signal of Some Different Medical Problems

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The term “polydipsia” refers to strong thirst and excessive drinking of fluids. Polydipsia isn’t a medical condition itself. But a number of different medical problems can cause polydipsia, including diabetes mellitus. In some situations, polydipsia might cause additional problems, like symptoms from a low sodium level (hyponatremia).

Symptoms

People with polydipsia often feel extremely thirsty. You might feel this way even though you’ve been drinking a lot of water or other fluids. That sensation of having a dry mouth just doesn’t go away. People with polydipsia may drink a lot of water, much more than they normally would. Depending on the situation, the sensation might build gradually over days or weeks, or it might start more suddenly.

Often people with polydipsia have a related symptom: polyuria. That just means that you are urinating a lot. You might notice a large volume of urine, and you might need to make a lot of trips to the bathroom.

Symptoms From Underlying Conditions

Some people with polydipsia have additional symptoms related to the cause of their problem. For example, someone with polydipsia due to type 1 diabetes mellitus might also have symptoms like the following:

  • Fatigue
  • Belly pain
  • Weight loss
  • Shortness of breath
  • Severe hunger

However, it’s important to note that diabetes is only one potential cause of polydipsia. (Also, not everybody who has diabetes notices this symptom.)

Symptoms From Drinking Too Much Water

Sometimes, people with polydipsia drink so much water that it causes additional symptoms. This might lead to a problem called water intoxication. That can happen when the excess water you drink lowers the concentration of sodium in your blood. This leads to something called “hyponatremia.” If severe, this can be a potentially life-threatening condition, leading to problems like the following:

  • Nausea and vomiting
  • Headache
  • Confusion and delirium
  • Tremors
  • Seizures
  • Difficulties with balance
  • Coma

Seek immediate medical attention if someone with polydipsia has serious symptoms like decreased responsiveness.

Theoretically, polydipsia might cause other complications over the long-term if it isn’t treated. These rarely might include problems like damage to the kidneys, gastrointestinal system, bladder, or heart.

Causes

Different types of issues can cause a person to develop polydipsia. To understand them, its helpful to understand a little about how your body regulates water.

Fluid Balance

Your body has a variety of physiological signals that it uses to regulate fluids. Water is present inside your body’s cells, and it is also present in other compartments of the body, like the bloodstream. If too much water enters these cells, that can cause problems, and if not enough enters, that causes problems as well. Your body works very hard to make sure that the right amount of water stays inside cells.

One of the ways it does this is through releasing hormones such as arginine vasopressin (AVP). Normally, AVP sends signals to both the brain and the kidneys. For example, if your body detects that it is dehydrated and needs more fluids, it sends signals to your kidneys to retain water, and it sends signals to your brain to make you thirsty. On the other hand, if you have plenty of fluid, it sends signals to the kidneys to urinate more, and it doesn’t send thirst signals to your brain. That helps your body keep the right amount of water inside.

Polydipsia From Underlying Medical Problems

Different medical problems with the fluid balance system may lead a person to develop polydipsia.

Diabetes Mellitus (“Sugar Diabetes”)

Both type I and type II diabetes mellitus can lead to polydipsia. (When people use the word “diabetes,” they are usually referring to either type I or type II diabetes mellitus.) 

Both of these types of diabetes mellitus can cause a person’s blood glucose (“blood sugar”) to get very high. More glucose than normal is present in the blood. But that has effects on other parts of the body, like fluid balance. Indirectly, the high level of glucose in the blood may mean that more glucose also ends up in your urine. This can cause more fluid to end up in your urine as well, leading to dehydration.

In an attempt to combat this, your body sends signals to the brain that you need to drink. In other words, you start to get thirsty. This can be thought of as a type of “compensatory polydipsia,” because your body is making you thirsty to try to correct underlying dehydration. In this case, the thirstiness is a natural response to being dehydrated.

Polydipsia with polyuria is a very common symptom in diabetes mellitus.

Diabetes Insipidus

Diabetes insipidus is another group of medical conditions that can cause polydipsia. Unlike diabetes mellitus (the kind more people are familiar with), diabetes insipidus has nothing to do with a person’s blood glucose. Instead, it is a problem with AVP, either in the way it is produced in the body or in the way the body responds to it. These problems might be genetic or from a problem that happens later.

A person can develop nephrogenic diabetes insipidus from a kidney problem. (For example, Sjogren’s disease affecting the kidney might cause nephrogenic diabetes insipidus). Central diabetes insipidus can result from a problem with the part of the brain where these hormones are produced (like from an injury after surgery).

In both cases of diabetes insipidus, the body is inappropriately making large amount of urine. Not surprisingly, this can cause you to get dehydrated. A person may also develop compensatory polydipsia, as the body signals the brain to try to drink fluids to correct the dehydration.

Other Medical Causes

Some other possible causes of polydipsia are:

  • Kidney failure
  • Conn’s syndrome
  • Addisonian crisis
  • Electrolyte abnormalities (like low blood potassium)
  • Obstructive uropathy
  • Bartter syndrome
  • Sickle cell anemia

Some drugs can make you feel thirsty and might lead to polydipsia as well. For example, some drugs of the anticholinergic type, (such as some used for depression) might make you feel thirsty.

Primary Polydipsia

Another important category is called “primary polydipsia.” This just means that increased water intake itself is the source of the problem and not the result of your body trying to correct your dehydration.

Sometimes a person might drink an excess amount of fluid because they thought it was healthy, or because a health professional told them to drink plenty of fluids. Some people drink too much plain water during sporting events. If you go overboard, this may cause significant health problems.

Some people also have what is called “psychogenic polydipsia.” This can happen in people with underlying mental health problems, like schizophrenia. It’s unclear exactly why this happens, but it seems that some psychiatric medications may worsen the problem.

Less commonly, some kinds of brain problems can cause another type of primary polydipsia called “dipsogenic polydipsia.” This can happen when the hypothalamus is injured (part of the brain involved in thirst). This might make you feel thirsty, even though you aren't dehydrated.

Diagnosis

People with polydipsia need medical attention and diagnosis to discover if some underlying disease might be causing polydipsia, like diabetes mellitus. If you have primary polydipsia, it’s also important to stop taking in excess water, because that can lead to water intoxication.

Your medical provider should ask you about your recent symptoms and your underlying medical conditions. You’ll be asked when your increased thirst started. Your clinician will also need to know about all your medications and any recent illnesses or surgeries. You’ll also need a full medical exam. 

Basic laboratory blood tests are a key part of diagnosis. For example, you might need tests like:

These can be helpful for diagnosis, but they are also critical to make sure you don’t have a serious problem from polydipsia, like hyponatremia.

Urine tests are often done. These can give an idea of how concentrated your urine is. That can give information about whether you have primary polydipsia or whether your thirst is because you are dehydrated and your body is trying to compensate.

Depending on the situation, you might need other tests. This might include a water deprivation test. (This shows how your body responds to an injection of AVP after drinking less water). Depending on the situation, you might need other tests, like a brain MRI, to rule out brain disease as a problem.

Treatment

Treatment will depend on the underlying medical condition.

For a person with primary polydipsia, the key is reducing water intake. This can reduce the risk of complications from overhydration. It can be a challenge for people with serious psychiatric symptoms. Education of patients and family member is key. Sometimes a change in psychiatric medication or behavioral therapy might be helpful. Some people might need to be regularly weighed as a way to double-check that they haven’t been drinking too much. The strategy will need to be tailored to the individual.

If you have an underlying medical condition, like type 1 or type 2 diabetes mellitus, these will require specific treatment. For example, treatment for type 2 diabetes mellitus might require dietary and exercise changes as well as medications.

If you have diabetes insipidus, you’ll need a different kind of treatment. Depending on the cause, this might include drugs that replace AVP in the form of a spray or tablet. Your health care provider will specifically tailor your treatment to you.

Treatment for Hyponatremia

Depending on its severity, hyponatremia might need immediate treatment in a hospital environment. Fluid restriction is the main part of treatment, and you may need careful monitoring. In this way, your health care team can safely raise blood sodium levels and prevent long-term complications. In rare cases, a person might need an intravenous infusion of sodium, but this must be done very carefully, to prevent other potentially serious health problems.

A Word From Verywell

Polydipsia is a symptom that can happen in a lot of different medical conditions. It might mean something simple, like needing to change one of your medications. However, it might be a sign of something more serious, like type 1 or type 2 diabetes mellitus. Best to have it checked out and address the issue directly. 

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