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What causes polydipsia (excessive thirst)?

by Josephine Andrews
Published: Last Updated on 395 views

Polydipsia means “much thirst”. Accordingly, those affected drink a lot and then usually excrete more urine. The strong thirst can be a sign of a physical illness such as diabetes mellitus. Learn about other causes of polydipsia, when to see a doctor, and how polydipsia is treated.

quick overview

  • What is polydipsia? excessive thirst, often a symptom of an underlying medical condition
  • Causes : e.g. severe fluid loss through vomiting, diarrhea or sweating, fever, diabetes mellitus, diabetes insipidus , malfunctioning of the thyroid gland or kidneys , psychological factors, certain medications
  • How are polydipsia and diabetes related? Depending on the type of diabetes, either the increased sugar concentration in the urine triggers polydipsia (diabetes mellitus) or a deficiency or ineffectiveness of the hormone ADH (diabetes insipidus).
  • When to the doctor? if the strong feeling of thirst lasts for days and/or is accompanied by other symptoms (frequent urination, weight loss, etc.).
  • What to do with polydipsia Depending on the cause, for example, drink a lot and compensate for loss of electrolytes (in the case of heavy sweating or diarrhea), treatment of the underlying disease

Polydipsia: Definition

Thirst is a natural and vital signal that the body needs more fluids – so we should drink something. to keep the fluid balance in balance.

The situation is different with polydipsia: Doctors understand it to mean an excessively increased feeling of thirst . It is usually a sign of a disease and often occurs together with polyuria – i.e. increased water excretion. As a result, there can be an alarming loss of fluid in the body.

This is how thirst arises

The thirst center is located in the brain , more precisely in the hypothalamus . There, specialized “probes” monitor the amount of fluid in the body (via blood volume) as well as the precise concentration of electrolytes (such as sodium and potassium ). A sense of thirst is now triggered when:

  • the “water level” in the body drops by at least half a percent (e.g. during strenuous exercise) or
  • the concentration of blood salts such as sodium is increased (e.g. by eating a bag of crisps) so that “dilution” becomes necessary.

Hormones are involved in regulating the fluid balance . One of these important messengers is ADH ( antidiuretic hormone ):

When there is a lack of fluids, the diencephalon releases ADH. It travels through the bloodstream to the kidneys, causing them to retain urine so the body doesn’t lose more fluid. The little urine that passes is highly concentrated and dark yellow.

With damage to the hypothalamus and with age, the feeling of thirst is often lost. Those affected then drink far too little, so that the fluid content in the body can drop sharply. Such drying out ( dehydration , in extreme cases: dehydration) can lead to death within a few days!

Polydipsia: causes and possible diseases

Polydipsia can have different causes, for example:

  • Thyroid diseases : Here, above all, the thyroid overfunction (hyperthyroidism) should be mentioned. The body produces too many thyroid hormones, which causes the metabolism to run at full speed. Common symptoms: unwanted weight loss despite a good appetite, nervousness, trouble sleeping, profuse sweating and polydipsia.
  • Cushing’s syndrome : Here, an excess of the hormone cortisol causes symptoms such as a full face, trunk obesity (bulky stomach, slim arms and legs), high blood sugar levels with polydipsia and polyuria, acne , muscle weakness, high blood pressure and fluid retention in the tissue (oedema).
  • Hypercalcemia (excess calcium in the blood): Possible causes are, for example, a disease of the parathyroid gland (hyperparathyroidism), malignant tumors and hypofunction of the adrenal cortex . Hypercalcemia can cause polyuria and polydipsia, among others.
  • Kidney disease : Changes in kidney tissue caused by inflammation or tumors can lead to abnormally high urine output or diabetes insipidus (see below).
  • Medications : As a side effect, some drugs increase thirst. These include, above all, diuretics. Taking the antidepressant lithium can also initially trigger polydipsia.
  • Psychological causes : In certain forms of obsessive-compulsive behavior and schizophrenia, but also at the beginning of anorexia, those affected often drink large quantities of liquid. However, they do not suffer from an increased feeling of thirst, which means that there is no physical reason for the increased drinking.
  • Fever : When the body temperature rises (due to various infections), the body loses more fluids, which often causes a strong feeling of thirst.
  • Diarrhea and Vomiting : Severe vomiting and/or diarrhea can cause the body to lose a lot of fluid and become dehydrated quickly. The motto here is: drink, drink, drink! Otherwise it can quickly become dangerous (to life)!
  • Brain damage : With certain types of brain damage, thirst regulation or the release of the hormone ADH can be disrupted. As a result, drinking behavior can change, for example in the case of traumatic brain injury , cerebral hemorrhage , contusion of the brain, cysts , tumors or inflammation in the area of ​​the hypothalamus or pituitary gland as well as after brain surgery.

Most importantly, polydipsia can occur with diabetes !

Link polydipsia & diabetes

A pathologically increased feeling of thirst and the associated excessive fluid intake are often also symptoms of diabetes mellitus (diabetes) and diabetes insipidus (water urinary dysentery).

Diabetes mellitus (diabetes)

Regardless of whether diabetes mellitus type 1 (congenital) or type 2 (acquired) – the effects are practically the same: the energy-rich blood sugar cannot be sufficiently absorbed into the body’s cells. The blood sugar level is abnormally high, which is why the body tries to excrete all the sugar through the urine – sugar binds a lot of water, so that those affected excrete a lot of urine (polyuria), which also tastes sweet. In addition, the high blood sugar level in diabetics triggers severe thirst (polydipsia).

Diabetes insipidus (water urinary dysentery)

As mentioned above, antidiuretic hormone (ADH) is important in regulating water balance. However, if there is a lack of ADH or if the kidneys do not respond sufficiently to the hormone (e.g. due to kidney disease), those affected excrete an excessive amount of urine (polyuria) – more than three liters a day! In addition, those affected suffer from severe thirst (polydipsia).

Polydipsia: when do you need to see a doctor?

For adults, drinking around two liters a day is usually sufficient. Sometimes the fluid requirement is also higher, for example during sports or after a very salty meal. Even as summer temperatures rise, it’s not uncommon for people to drink more. An increased feeling of thirst does not always require an immediate visit to the doctor.

However, if your severe thirst persists for days and you drink excessive fluids and/or have any of the following symptoms, you should consult a doctor:

  • weight loss
  • frequent and increased urination

Polydipsia: what does the doctor do?

The doctor must first clarify the cause of polydipsia. To do this, he will first ask you about your medical history (anamnesis). For example, he asks:

  • How long have you felt thirsty?
  • How much do you drink a day?
  • What drinks do you drink?
  • What medication are you taking?
  • Do you have any other symptoms such as fever, diarrhea or vomiting?

The subsequent physical examination includes, among other things, a blood pressure measurement and a blood draw. During the blood test , attention is paid to the blood sugar levels and the amount of various electrolytes, among other things. Also important is a urine test , in which the sugar concentration in the urine is measured – a lot of sugar in the urine indicates diabetes mellitus.

If there is a suspicion of diabetes insipidus, the doctor can carry out a so-called “ thirst test” on you: You are not allowed to eat or drink for a period of several hours. The doctor observes your physical reaction to thirst and determines your body weight and various blood values ​​every hour.

A “thirst test” is not exactly pleasant for those affected, as an almost unbearable feeling of thirst sets in. In addition, this examination does not necessarily allow conclusions to be drawn about the cause of polydipsia. For this reason, scientists developed a test in 2018 that is said to be more suitable: This determines whether the hormone ADH is no longer produced sufficiently or is no longer effective in the kidneys, or whether polydipsia is caused by a disturbance in the sense of thirst. This test has already been used, for example, at the Leipzig University Medical Center.

Once the cause of polydipsia is identified, the doctor can suggest appropriate treatment . In the case of diabetes, this includes, for example, regular physical activity, a healthy diet, reducing excess weight and, if necessary, blood-sugar-lowering medication.

Polydipsia: You can do this yourself

The need to drink usually increases because the body excretes more water – for example, in the case of a feverish illness or a gastrointestinal infection with vomiting and/or diarrhea. Since the body also loses minerals (electrolytes) with the urine, you should also compensate for this deficit as quickly as possible. Thus:

  • drink a lot
  • Replace lost electrolytes, for example with a water-salt-sugar solution with the right composition (e.g. ready-made electrolyte solution from the pharmacy)

Prevent excessive thirst

You can prevent non-disease-related polydipsia with the following tips:

  • Alcohol only in combination with water : Alcohol removes water from the body. After a wet, happy night, you often wake up in the morning with a strong thirst and a headache . For prevention, it is best to drink a glass of water after each glass of alcohol . This equalizes the liquid level again.
  • Caffeine in moderation : Caffeine in coffee or black tea acts as a diuretic and inhibits ADH production. The body gets used to the caffeine so that regular consumption no longer removes an excessive amount of water. At best, however, you should drink a glass of water with every cup of coffee – and according to an Australian study, less than six cups a day. Otherwise the blood pressure increases and with it the risk of cardiovascular diseases.
  • Avoid sweet drinks : Sweet fruit juices and sodas often do not quench thirst, but rather increase the feeling of thirst. Therefore, you should rather drink water, fruit juice spritzers or unsweetened fruit tea.
  • Drink enough during sports and heat : During sports and at high temperatures in summer, you should pay particular attention to ensuring that you drink enough fluids. Experts recommend 1.5 to three liters per day, depending on body weight and sweat loss.
  • Mixing salt in the water : In hot countries, fresh juices often have a small pinch of salt added to them – this not only quenches thirst but also restores the lost electrolytes. So polydipsia has little chance.

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