What Is Polydipsia?

  • Asha Moalin Master’s degree in Healthcare Technology, University of Birmingham
  • Laura Hawkins Doctor of Medicine - MB BCh BAO - Belfast medicine, Queen’s University
  • Richa Lal MBBS, PG Anaesthesia, University of Mumbai, India

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Introduction

Polydipsia is a medical condition, meaning an excessive thirst, causing an individual to drink a vastly increased amount of fluids in a day.1 With polydipsia, you may feel thirsty for days, weeks or sometimes months and not be able to quench your thirst despite how much you drink. The word polydipsia comes from the Greek word “Poludipsios”, which means “very thirsty”. Polydipsia is a symptom of an underlying medical condition.1

In a healthy individual, feeling thirsty is normal as it signals that your body requires hydration but if you feel thirsty all the time, even after drinking fluids, you should consult your doctor.2 Polydipsia is often a sign of a serious health condition such as diabetes mellitus, diabetes insipidus, dehydration, infection (like sepsis) or psychogenic polydipsia associated with psychiatric disorders. Understanding polydipsia as a symptom means that other medical conditions can be diagnosed.

Causes of polydipsia

Thirst is a normal response to your body losing fluids and is signalling to you to drink more liquid. This is to maintain homeostasis (a steady state) in the body and to allow the body to function normally. You may become thirsty due to:

  • Eating salty or spicy food
  • Drinking a lot of caffeine or alcohol
  • Sweating and exercising
  • Diarrhoea and vomiting
  • Significant blood loss
  • Pregnancy
  • Some prescription medicines

However, polydipsia is an excessive thirst and can be caused by physiological and psychogenic medical conditions.

Physiological causes

A physiological cause is a physical condition that occurs within the body and affects how the body normally functions. Polydipsia and polyuria (an increase in the frequency of urination)are symptoms connected with diabetes, and the increase in thirst is caused by abnormally high blood glucose levels. 

Diabetes mellitus

Diabetes mellitus, more commonly known simply as diabetes, is a medical condition where the body is unable to control the blood sugar concentration. There are two types of diabetes:

  • Type 1–an autoimmune disorder where the body’s immune system attacks the cells that make insulin, meaning that the body is unable to regulate the levels of glucose
  • Type 2 diabetes–this occurs when the body either does not produce enough insulin or has become resistant to the insulin produced. This is commonly caused by lifestyle factors.

Symptoms of diabetes mellitus include feeling thirsty (polydipsia), urinating often (polyuria), and feeling tired. Some people may experience weight loss or find that cuts and scratches take longer to heal. Diabetes can also make you more prone to infections such as thrush.

Diabetes insipidus

This is a rare condition not related to diabetes mellitus. This occurs when the body produces too much urine due to an abnormality with the antidiuretic hormone (ADH). ADH is important in regulating fluids in the body and is released by the hypothalamus when the fluids in the body get too low, causing the body to produce more concentrated urine. In diabetes insipidus, ADH is not produced when fluid levels are low, which means that urine is not concentrated, leading to too much fluid loss. This causes polydipsia to occur as the body tries to compensate for the loss of water by drinking an excessive amount of water.2

Dehydration

A lack of drinking fluids is a common cause of polydipsia. Dehydration is caused when the body has more fluids leaving the body than it is bringing in. It could be caused by sweating or losing fluid through diarrhoea and vomiting. 

Psychogenic causes

Mental health disorders

Polydipsia may be present in people with developmental disorders, such as autism and those with psychiatric disorders like bipolar disorder, psychotic depression and schizophrenia. Up to 18% of patients with mental health disorders have polydipsia.1 The causes of psychogenic polydipsia are not fully understood, but in some disorders, patients can compulsively drink water and other fluids, leading to excessive water intake and abnormal amounts of urination. 

In people who have schizophrenia and polydipsia, MRI scans of their brains show a smaller hippocampus. This leads to irregularities in ADH secretion. This means that the individual will not be able to regulate the water content in their body and will urinate a large volume of dilute urine even if the body has lost fluid. This leads them to be excessively thirsty.4

Medication side effects 

Medications themselves can also cause polydipsia. Anticholinergic medications can cause you to have a thirst that cannot be quenched.1 Anticholinergic drugs are used to block the neurotransmitter acetylcholine.3 They are used to treat diseases like COPD, overactive bladder, and Parkinson’s disease. The effect on the neurotransmitter acetylcholine can impact the release of the ADH hormone. This then results in excessive drinking with ongoing feelings of thirst.1

Symptoms

Feeling thirsty is a normal human response to loss of fluid loss, but there are symptoms which indicate polydipsia:

  • Persistent thirst, regardless of how much water you drink
  • Drinking an abnormal amount of fluid, above 3 litres a day
  • Urinating more than 5 litres of urine each day

Potential complications

Polydipsia can lead to hyponatraemia, where the sodium level in the body is below the normal range of 135-145 milliequivalents/litre.1

This can lead to the following symptoms:

  • Nausea and vomiting
  • Blurred visions
  • Dizziness and tremors
  • Confusion and fatigue
  • Seizure

Hyponatraemia can be fatal and can lead to death or severe permanent neurological damage if not treated appropriately.1

Diagnosis of polydipsia

Polydipsia can be diagnosed by:

  • Taking a medical history
  • Physical examination
  • Laboratory tests measuring blood glucose levels and serum electrolytes (essential salts and minerals in the blood)

Medical history

During an appointment with your doctor, they will need to take a detailed medical history to formulate a diagnosis.5 There are several questions they may ask you, including:

  • When did the excess thirst begin? 
  • Did it happen gradually or all of a sudden?
  • How long have you been thirsty and does drinking fluid alleviate the thirst?
  • Are you urinating more frequently?
  • Does the level of thirst change throughout the day?
  • Have you increased your exercise? Are you sweating more?
  • Have you changed your diet to include more salty or spicy food?
  • Has your weight changed unexpectedly? 

Doctors may also ask for a history of any recent lifestyle changes to determine any alcohol intake and how much fluid is normally consumed. A detailed medical history should include details of psychiatric illness, systemic brain disorders, injury to the brain, and autoimmune disease.1,2

Physical examination

A doctor will also perform a physical examination to aid in diagnosis. This may include:

  • Eye test to detect blurry vision
  • Take urine samples
  • Do a fluid deprivation test - where the doctor will ask the patient to drink less fluid over a certain period. This may depend on whether the patient is diabetic or has underlying diabetes insipidus as this can lead to dehydration1,8

To rule out psychogenic causes, a doctor may request MRI or CT scans of the brain.

Laboratory testing

Doctors may request laboratory tests to diagnose polydipsia and determine what is causing it. They may test and measure:

  • Blood glucose levels
  • Complete blood count
  • Calcium blood levels
  • Sodium blood levels
  • Electrolytes

Lab work may also include serum osmolality, urine volume, and urine electrolytes.1 

Treatment options

Depending on the doctor’s examination and the results from the laboratory tests, treatment will look to address the underlying causes, incorporating lifestyle changes and medications.5,

Treating underlying causes

If the tests show that the patient has diabetes mellitus, doctors will recommend treatments to help control blood sugar levels. This will depend on what type of diabetes you have:

  • Type 1 diabetes will require regular insulin injections
  • Type 2 diabetes may require medicine to control blood glucose levels or an individual may be able to reduce their blood sugar through lifestyle changes. 

If you are diagnosed with diabetes insipidus, then doctors may inform you to increase the amount of water you drink to prevent dehydration and feeling excessively thirsty. Desmopressin can be prescribed, which mimics the function of ADH and can help alleviate polydipsia.

From the medical history, doctors may recognise certain medications that can cause polydipsia and can change your prescription or alter the dosage of current medication accordingly.2 

Lifestyle changes

A doctor may recommend that you control your fluid intake and can advise you to take counselling to assist with lifestyle changes. When you are in control of how much you drink, you can alleviate the symptoms of polydipsia, especially if there are no underlying medical conditions that explain polydipsia. Other lifestyle changes include changing diet to reduce salty and spicy food, exercising and keeping a healthy weight, and sleeping well.

Medication

There have been several clinical trials investigating the potential uses of medicines to treat polydipsia but they have not been implemented into clinical use yet. Potential drug types currently being investigated include:1

There is no proven “one-size-fits-all” treatment plan for polydipsia and it will depend on each patient, laboratory test results and the expertise of the doctors. You may be referred to a specialist depending on your treatment requirements.

Complications and risks

Polydipsia, if not treated, can lead to hyponatraemia and can impact kidney function.6,7 

Hyponatraemia

As described earlier, hyponatraemia is a medical condition where the sodium concentration in the blood is below average due to excessive drinking and excessive urination. Sodium is essential for normal body function as it is involved in:

  • Blood pressure control
  • Nerve and muscle control
  • Control of fluids in the body

When the sodium concentration in the blood is too low, the water will go inside the cells causing them to swell. This can be dangerous if it occurs in the brain which could lead to swelling in the brain which can be fatal if not treated appropriately.

Kidney function

As polydipsia causes excessive urination, there is an increase in kidney function.1 To compensate for the increase in fluid volume, the body will not release ADH, causing a large dilute volume of urine to be produced by the kidney. This means that there is an increase in filtering of the blood to remove the excess water and this increase in kidney burden can have an impact on kidney function. Polydipsia can cause the kidney to reduce fluid output from 12L per day to 8L per day or even less.1

Prevention

Depending on the underlying conditions, there are several ways to prevent excessive drinking:

  • Drink more water and reduce your consumption of sugary drinks
  • Decrease or avoid drinks containing caffeine like coffee or tea
  • Avoid drinking alcoholic drinks
  • If you have diabetes, monitor blood sugar levels using testing equipment if you become very thirsty

Monitoring how much water you drink and being aware of what types of drinks you are drinking is another way to prevent overdrinking and its complications. Undergoing regular medical checkups, especially if you are concerned, can be done to prevent polydipsia and can be an opportunity to diagnose and treat any underlying medical conditions. 

Summary

Polydipsia is characterised by a persistent thirst that is not quenched despite drinking an excessive amount of fluid. This then leads to increased urination. Polydipsia is a symptom of underlying medical conditions such as diabetes mellitus, diabetes insipidus or kidney failure. Diagnosis requires a mix of laboratory testing of blood and urine samples and taking a detailed medical history. 

Treatment will depend on the underlying medical condition, and lab results, and may require counselling. As such there is no common treatment and management can differ between individuals. You may be referred to a specialist if you require specialist treatment but this will be communicated to you by your doctor. 

If you are feeling thirsty all the time, and it is not relieved by drinking fluids, you may have an underlying medical condition that could be serious. If you suspect that you might have polydipsia, see your doctor for examination and testing.  

References

  1. Kotagiri, Rajesh, and Gurusaravanan Kutti Sridharan. ‘Primary Polydipsia’. In StatPearls. Treasure Island (FL): StatPearls Publishing, 2023. http://www.ncbi.nlm.nih.gov/books/NBK562251/
  2. Ahmadi L, Goldman MB. Primary Polydipsia: update. Best Pract Res Clin Endocrinol Metab [Internet]. 2020 [cited 2024 May 10]; 34(5):101469. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7683824/
  3. Ghossein, Noah, Michael Kang, and Anand D. Lakhkar. ‘Anticholinergic Medications’. In StatPearls. Treasure Island (FL): StatPearls Publishing, 2023. http://www.ncbi.nlm.nih.gov/books/NBK555893/
  4. Christ‐Crain M, Winzeler B, Refardt J. Diagnosis and management of diabetes insipidus for the internist: an update. J Intern Med [Internet]. 2021 [cited 2024 May 10]; 290(1):73–87. Available from: https://onlinelibrary.wiley.com/doi/10.1111/joim.13261.
  5. Christ-Crain M. EJE AWARD 2019: New diagnostic approaches for patients with polyuria polydipsia syndrome. European Journal of Endocrinology [Internet]. 2019 [cited 2024 May 10]; 181(1):R11–21. Available from: https://academic.oup.com/ejendo/article/181/1/R11/6654173.
  6. Chamberlain L. Hyponatremia Caused by Polydipsia. Critical Care Nurse [Internet]. 2012 [cited 2024 May 10]; 32(3):e11–20. Available from: https://aacnjournals.org/ccnonline/article/32/3/e11/4456/Hyponatremia-Caused-by-Polydipsia.
  7. Evanson DJ, Espiridion ED, Evanson DJ, Espiridion ED. The Catastrophic Effects of Psychogenic Polydipsia: A Case Report. Cureus [Internet]. 2023 [cited 2024 May 10]; 15(9). Available from: https://www.cureus.com/articles/183649-the-catastrophic-effects-of-psychogenic-polydipsia-a-case-report
  8. Pedrosa W, Drummond JB, Soares BS, Ribeiro-Oliveira A. A Combined Outpatient and Inpatient Overnight Water Deprivation Test is Effective and Safe in Diagnosing Patients with Polyuria-Polydipsia Syndrome. Endocrine Practice [Internet]. 2018 [cited 2024 May 10]; 24(11):963–72. Available from: https://linkinghub.elsevier.com/retrieve/pii/S1530891X20354677.

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This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Asha Moalin

Master’s degree in Healthcare Technology, University of Birmingham

Asha is a recent graduate with a Master’s degree in Healthcare Technology from the University of Birmingham. With a passion for innovating medical therapies and technologies, Asha is dedicated to contributing advancements that allow patients to lead longer and healthier lives.

Her expertise includes both laboratory research and comprehensive literature reviews. Drawing on several years of academic writing, Asha enjoys translating complex data into accessible and informative articles.

She is committed to bridging the gap between scientific intricacies and public understanding. Beyond healthcare, Asha also possesses exposure to the business world. This is evident in her work experience at J.P Morgan chase and Turner & Townsend, where she explored finance, consultancy and sustainability. These experiences have equipped her with a diverse skill set and understanding of the connection between healthcare and business.

my.klarity.health presents all health information in line with our terms and conditions. It is essential to understand that the medical information available on our platform is not intended to substitute the relationship between a patient and their physician or doctor, as well as any medical guidance they offer. Always consult with a healthcare professional before making any decisions based on the information found on our website.
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