Excessively consuming water can point towards a cause or an effect of being afflicted with kidney disease.¹ This condition of consuming water excessively is termed polydipsia.² In this article, we talk about the intricate relationship between polydipsia and kidney disease, looking at the potential causes and mechanisms, diagnostic criteria, disease management, and treatment options, and also taking a look at how kidney disease could lead to polydipsia and how the disorder could lead to worsening in renal dysfunction.

What exactly makes a kidney diseased?

The kidneys are the two-bean-shaped organs, situated closer to the back. About the size of your fists, they filter the waste product and excess water out of your blood, making it into urine. In circumstances where the kidney is diseased, it usually implies that they are unable to filter out blood accurately in the manner that they should be. Leaving impurities in the blood, causing issues that can impact future health.

Figure 1. Cartoon image of two kidneys.

Damaged kidneys can lead to fluid build-up within the body, as a result of improper filtration. This can then lead to feeling nauseated, weakness, ankles swelling up, shortness of breath, and poor quality of sleep. If left untreated, it can prove to be life-threatening. 

One way to combat this and keep your kidneys healthy is to moderately increase water intake. Thereby, increasing blood flow to the kidneys and promoting efficient waste removal. Reducing the storage of urine in the kidneys can further lead to the development of kidney stones.⁴

What is polydipsia?

Although drinking water is meant to be a good habit to involve in your everyday lifestyle. When there is a frequent sign of excessive thirst, encouraging you to consume fluids in excess, it could be a serious condition pointing towards the development of polydipsia. The word “polydipsia” comes from the Greek word “poly” which translates to “excessive” and “dipsia” is “thirst”. 

Production of urine in excess, in quantities greater than 40-50 ml/kg within a period of 24 hours could point towards polyuria. Usually occurring together, this is known as polyuria-polydipsia syndrome, and it is quite a rare condition.

Polydipsia often presents itself as a compensatory mechanism in response to certain conditions that tend to disrupt the body’s fluid balance and lead to dehydration. Such as, in kidney disease, when the kidneys tend to lose their ability to concentrate urine properly. Triggering a sense of thirst, due to increased urination as a consequence of faltered electrolyte balance and other such issues. 

Whom does polydipsia affect?

Primarily seen in patients with developmental disorders such as learning and intellectual disabilities and autism. As well as in patients suffering from psychiatric disorders such as psychotic depression, bipolar disorder, schizoaffective disorder, schizophrenia, etc. Other patients with anxiety and panic disorders can be prone to developing polydipsia due to behaviours such as compulsory water drinking. Such behaviours can also be seen in excessively health-conscious or physically active individuals as well, who fall into the habit of drinking excess amounts of fluids.

Apart from that, polydipsia can affect individuals from any demographic group, occurring in people with varied lifestyles and medical conditions. A few groups of people who might be susceptible to developing this disorder are, individuals with:

• Diabetes
• Hypercalcemia (high levels of calcium)
• Hyperthyroidism (overactive thyroid gland)
• Kidney disease

How can impaired kidneys cause polydipsia?

• Metabolic Acidosis: Disturbances in acid-base concentrations, usually seen in advancing kidney diseases
• Alterations in renal function: When afflicted with kidney disease, an individual’s kidney function is impaired, leading to the improper secretion of the antidiuretic hormone. This can cause imbalances in the reabsorption of water and electrolytes
• Electrolyte imbalance: When the levels of electrolytes in the blood, i.e. potassium and sodium, are affected, it can lead to excessive depletion of it with urine, stimulating more fluid intake due to thirst and urine output as a mechanism to compensate

Symptoms of kidney disease-related polydipsia

When the body perceives itself as dehydrated and unable to feel satiated regardless of the amount of water consumed, it begins to display several symptoms to combat this constant sensation and need to drink water. Some of which may be:

• Passing large quantities of urine per day (>40/50 ml/kg in a day)
• Abnormal feelings of hunger
• Exhaustion and fatigue
• Vision going blurry
• Persistent feeling of a dry mouth 
• Feelings of disorientation or dizziness
• Muscle spasms
• Unexplained seizures 

Some kidney diseases can cause polydipsia

Several kidney diseases can occur with polydipsia coming up as one of their symptoms. They include:

• Nephrotic syndrome: leaking of some proteins into urine
• Polycystic kidney disease (PKD): formation of cysts filled with fluid within the kidneys
• Diabetic nephropathy: kidney damage that is driven by diabetes
• Glomerulonephritis: inflammation of the glomeruli, clogging up kidney filters with proteins 
• Chronic kidney disease: kidneys failing to function for a prolonged time period 

Diagnosis of polydipsia with kidney disease

Laboratory tests

Measuring an individual’s antidiuretic hormone levels, serum and urine osmolality can help aid in differentiating between the two different types of polydipsia in kidney disease. 

Clinical evaluation 

By assessing the individual’s serum electrolyte levels in a blood test fluid intake history, and urine output; a healthcare professional can help narrow down the symptoms and differentially diagnose the symptoms as polydipsia.

Imaging studies

Renal imaging modalities, such as computer tomography scans and ultrasound scans, can be used to evaluate the structural integrity and examine the renal pathology of the kidneys in order to see how it contributes to polydipsia.

Managing and Treating polydipsia

Fluid restriction

By noticing and managing one's fluid intake, if it turns the urine too clear, instead of it having a slight yellow tinge to it, could denote loss of electrolytes with the urine. The patient can limit their fluid intake and reduce the amount of electrolytes lost, regaining balance in the kidneys in order to prevent fluid overload in the body.

Dialysis

When the kidney disease paired with polydipsia gets chronic, and cannot be treated through regular means or via medication, haemodialysis, and peritoneal dialysis paired with renal replacement therapy can prove to be effective as well as necessary for patients suffering from chronic, end-of-stage kidney disease and severe fluid overload following polydipsia.

Pharmacological medication

Upon visiting one’s healthcare provider, they could help with the prescription of medications that action or increase the secretion of the antidiuretic hormone, such as vasopressin or desmopressin receptor antagonists that could be picked to deal with the cases of polydipsia associated with diseased kidneys. They help with reducing the urge to drink and prohibit excessive thirst sensations. 

FAQs

Does kidney disease cause polydipsia?

Kidney disease does not itself lead to polydipsia but can lead to certain complications that cause polydipsia. Conditions such as electrolyte imbalance, acid-base or inadequate fluid regulation lead to feelings of thirst and polydipsia as a compensation mechanism of the body due to a decrease in antidiuretic hormone. 

What diseases cause polydipsia?

Polydipsia can be caused due to a variety of diseases, some of them being: 

• Diabetes insipidus (a water balance disorder)
• Diabetes mellitus (both type 1 and 2)
• Hypercalcemia (increased levels of calcium in the blood)
• Hyperthyroidism (increased activity of the thyroid) 
• Psychiatric disorders leading to individuals increasing their water intake 

Can you have polydipsia but no polyuria?

In most circumstances, polyuria occurs with polydipsia, known as polyuria-polydipsia syndrome. When there is an excess consumption of fluids, the body tries to combat this by increasing urine production in the body. Although, one can exist without the other, in some instances. For example, when recovering from an infection.

What are the long-term effects of polydipsia?

Prolonged polydipsia, especially if left untreated or if the underlying cause is not addressed, can lead to several long-term effects:

• Dehydration: Inadequate intake of electrolytes along with excessive water consumption can lead to dehydration, which can affect various bodily functions and potentially lead to serious complications
• Electrolyte imbalances: Excessive water intake without adequate electrolyte replacement can disrupt the balance of electrolytes in the body, leading to symptoms such as weakness, fatigue, muscle cramps, and irregular heartbeat
• Kidney damage: Chronic polydipsia may put a strain on the kidneys, potentially leading to kidney damage or exacerbating existing kidney conditions
• Central nervous system effects: In severe cases, chronic polydipsia may affect the brain and central nervous system, leading to neurological symptoms such as confusion, seizures, or coma

It's important to identify and address the underlying cause of polydipsia to prevent these long-term complications. Treatment may involve managing the underlying condition, regulating fluid intake, and addressing any electrolyte imbalances.

Summary

Polydipsia - the condition where one experiences excessive feeling of thirst - and kidney disease are intricately linked. In the case of these conditions, correlation (most times) leads to causation. Where one exists with the other, due to kidney irritation and improper filtration and imbalances in the electrolytes within the body. In order to combat this, we must recognise the clinical and diagnostic challenges. The individual must reduce fluid intake and seek clinical intervention when necessary. Checking their hormone and serum levels when one is urinating in excess (5000 mL in 24 hours). Further moving to dialysis and other treatments when necessary. 

But at the same time, moderation is key. Drinking water is still a crucial part in maintaining good health and kidney function, ensuring to consume at least 8-9 cups of water per day to avoid kidney disease and result in the onset of polydipsia instead.