Understanding Polydipsia

What Is The Medical Term Polydipsia?

The medical term polydipsia means excessive thirst. Thirst is the body’s way of telling you to rehydrate (physiologically increase water intake), for example, after an intense workout, after eating spicy or salty foods, or after drinking too much caffeine or alcohol.

However, polydipsia refers to feeling thirsty all the time, even after drinking enough fluids. If you can’t seem to quench your thirst, no matter how much water you drink, it might be polydipsia. Excess thirst can be a sign of an underlying health condition such as diabetes mellitus or diabetes insipidus, which should be properly diagnosed and treated.

Polydipsia vs Polyuria

Polydipsia is excessive thirst. Polyuria is excessive urination or increased urine output. Polydipsia and polyuria can occur together in certain health conditions such as diabetes.

Primary Polydipsia

Primary polydipsia means excessive drinking of water, more than what your body needs. In other words, you drink water excessively even though there is no underlying dehydration or fluid imbalance in your body. Primary polydipsia can be classified into two types described below: psychogenic polydipsia and dipsogenic polydipsia.

Different Types of Primary Polydipsia

Psychogenic polydipsia is a type of primary polydipsia that can occur in certain psychiatric disorders such as schizophrenia, bipolar disorder, and psychotic depression. It is a behavioral manifestation of the psychiatric disorder.

Dipsogenic polydipsia, also called compulsive water drinking, is a type of primary polydipsia that occurs due to a brain dysfunction where the hypothalamus, the part of the brain that controls thirst, is damaged or injured, causing you to feel thirsty even when your body doesn’t need more water. Additionally, dipsogenic polydipsia is also caused by the belief that drinking excessive water is essential for good health.

While ensuring your body is well-hydrated is vital for overall health, the recommended amount may vary depending on age, activity levels, and health history. If you have kidney disease or heart problems, make sure you discuss the recommended daily fluid intake with your doctor.

Secondary Polydipsia

Secondary polydipsia is the excessive intake of fluid due to thirst caused by a medical condition or medication. Common causes of secondary polydipsia include:

Dehydration

Dehydration can occur from not drinking enough fluids, excessive sweating, or illnesses that cause fever, vomiting, or diarrhea. Lack of enough fluids in the body (dehydration) can lead to excess thirst (polydipsia) and excessive fluid intake because the body tries to correct the lack of fluid. This type of polydipsia (excessive thirst) is usually short-lived and goes away once you rehydrate.

Diabetes Mellitus

In people with diabetes mellitus type 1 and type 2, hyperglycemia (high blood glucose levels) causes increased urination because the kidneys try to get rid of glucose in the urine, which is accompanied by excessive fluid loss in urine (polyuria). This is a compensatory polydipsia, where your body makes you thirsty to try and correct the dehydration caused by frequent urination.

Diabetes Insipidus

Diabetes insipidus is a condition in which there is a deficiency of or an altered response to arginine vasopressin (AVP, also called ADH or antidiuretic hormone), a hormone that regulates fluid balance in the body. Decreased AVP results in increased urine output and dehydration, causing excessive thirst or polydipsia.

Diabetes insipidus can develop due to kidney problems, for example, Sjogren’s syndrome. This is called nephrogenic DI. It can also be central diabetes insipidus, resulting from damage to the pituitary gland or hypothalamus, the parts of the brain that make fluid-controlling hormones.

Other Medical Causes

Other medical conditions that can cause polydipsia (excessive thirst) include low potassium, burns, sepsis, kidney failure, liver failure, congestive heart failure, Addison’s disease, Conn’s syndrome, Bartter syndrome, obstructive uropathy, and sickle cell disease.

Medication-Induced Polydipsia: What Drugs Cause Polydipsia?

Certain over-the-counter and prescription drugs can cause polydipsia as a side effect, the most common being diuretics or water pills. This is a compensatory polydipsia to correct dehydration caused by frequent urination that occurs as a result of taking diuretics (water pills).

In addition, certain medications used to treat psychiatric disorders, such as antipsychotics and mood stabilizers, can cause or worsen polydipsia. Excessive thirst can also be due to side effects of medications, such as dry mouth. Check out what medications can cause frequent urination.

Polydipsia Symptoms

Common Symptoms

Feeling thirsty even with sufficient fluid intake
Extreme thirst (being unable to quench your thirst, no matter how much water you drink)
Dry mouth or dry lips
Polyuria (excessive urination with increased urine output)

Differentiating Symptoms in Diabetes

Additional symptoms of diabetes include:

Type 1 diabetes mellitus: Polydipsia (excessive thirst), polyuria (excessive urination), polyphagia (excessive hunger), bedwetting in children, unexplained weight loss, irritability, tiredness, and blurry vision.
Type 2 diabetes mellitus: Polydipsia (excessive thirst), nocturia (increased urination at night), unexplained weight loss, tiredness, slow healing wounds, blurred vision.

Symptoms in Psychiatric Disorders: What Is Polydipsia In Mental Illness?

Psychogenic polydipsia is a type of primary polydipsia (excessive thirst) that often occurs in people with a psychiatric disorder such as schizophrenia. People with psychotic disorders and psychogenic polydipsia have an intense desire to drink water (compulsory water-drinking behavior and consumption of excessive quantities of fluids). This abnormal urge in people with mental illnesses can lead to fluid intake from any available source, including ingested fluid from toilets and showers.

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Complications of Polydipsia

Effects of Untreated Polydipsia

Excessive fluid intake in primary polydipsia can lead to serious health complications related to water toxicity. Signs and symptoms of too much fluid in the body may include nausea, vomiting, headache, confusion, delirium, seizures, and coma. Treatment includes correcting both the water imbalance and treating the underlying cause.

Excessive fluid intake in secondary polydipsia does not typically cause problems, because it is the underlying health condition that is triggering dehydration, and the excessive thirst is due to fluid loss. However, fluid balance in the body is precisely controlled through homeostatic regulation. Rarely the excretory capacity of the kidneys can become overwhelmed by the excessive fluid intake, causing problems.

Hyponatremia or Water Intoxication

Excessive drinking of water can lead to water intoxication and hyponatremia (low serum sodium level). Water intoxication is a life-threatening water imbalance that occurs due to excess water intake and too much fluid in the body. It can lead to hyponatremia, a condition where sodium levels in the blood drop below 135 milliequivalents per liter (mEq/L). Hyponatremia can cause cells to swell, which can lead to serious health complications.

Signs and symptoms of life-threatening hyponatremia and disrupted water balance in the body may include headache, nausea, stomach cramps, slurred speech, lethargy, confusion, delirium, seizures, coma, and death.

Diagnosis and Evaluation

Diagnostic Criteria

If you have polydipsia (excessive thirst), your healthcare provider will first rule out behavioral causes such as drinking water in excessive quantities. They will then try to identify an underlying cause for polydipsia. Evaluation will include a thorough medical history, physical examination, and diagnostic tests.

Common Diagnostic Tests

Blood tests such as fasting blood glucose, basic metabolic panel, electrolyte panel, and vasopressin or antidiuretic hormone (ADH).
Urine tests include urinalysis (appearance and osmolality (concentration) of urine), tests to detect glucose in urine, and measurements of daily urine output.
Water deprivation test to see how your body responds to an injection of ADH after drinking less water. People with diabetes insipidus continue to produce large volumes of dilute urine even though water deprivation should lead to small volumes of concentrated urine.
Imaging studies of the kidneys and brain.

Differential Diagnosis

The main differential diagnosis for primary polydipsia is diabetes insipidus. A water deprivation test (WDT) is a common diagnostic method for differentiating between these conditions. This test measures arginine vasopressin (AVP) activity and your body’s response to less water intake.

It's important to correctly diagnose polydipsia because there are distinct alterations in the treatment of different conditions. An incorrect diagnosis can lead to serious complications. For example, misdiagnosis of primary polydipsia as central diabetes insipidus may lead to treatment with desmopressin (a synthetic analog of vasopressin or antidiuretic hormone), which can cause severe hyponatremia (dangerously low blood sodium levels).

Treatment and Management

Behavioral Interventions

While hydration is important, excessive fluid intake can be harmful. If your polydipsia is due to behavioral causes, your doctor may recommend making behavioral changes to limit fluid intake. This may include:

Avoiding overhydration and limiting intake of water to 2.7 liters or 11.5 cups (for women) and 3.7 liters or 15.5 cups (for men), which is considered adequate daily fluid intake for healthy adults
Avoiding caffeinated and alcoholic beverages, which can cause excessive thirst
Adjusting fluid intake to a urine output of about 1.5 liters in 24 hours, which indicates healthy hydration levels in the body

Pharmacological Treatments

Pharmacological treatments for polydipsia will depend on the underlying medical condition causing the symptoms. For example, if you have diabetes mellitus, your doctor may prescribe diabetes medications to control blood sugar levels.

Management of Underlying Conditions

Based on the cause of polydipsia (excessive thirst), your healthcare provider will recommend treatments for the underlying condition.

For example, diabetes mellitus may be treated with healthy lifestyle changes and medications to lower blood glucose levels.

Treatment for central DI (diabetes insipidus) may include desmopressin (DDAVP, Nocdurna) to replace ADH.

Treatment for nephrogenic diabetes insipidus may include eating a low-salt diet and taking medications such as hydrochlorothiazide (Microzide) - this is a diuretic (water pill) that usually increases urine output but can decrease excessive urine in people with nephrogenic diabetes insipidus.

If a medication is causing polydipsia, your healthcare provider may adjust the dosage or switch you over to a different drug.

Treatment for psychogenic polydipsia in psychiatric patients may include medications to treat the symptoms of a severe mental illness, counseling with a mental health professional to help limit water consumption, and medications such as demeclocycline, which inhibit ADH and can be used off-label to improve hyponatremia.

Treatment for primary polydipsia essentially consists of controlling excessive water intake.

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