Too much water is a disease

Increased thirst

Increased thirst: overview

So that the body cells can fulfill their tasks, they need the right amount of water and substances dissolved in it. Sensors therefore constantly report the current salt and water levels to the thirst center in the brain. If certain substances are too concentrated in the blood, so to speak, the blood is too "thick", the brain ensures that the kidneys hold back water, thirst arises and the person drinks enough. In this way, the balance in the blood can usually be restored, for example if you sweat heavily. Incidentally, this also means that the body's water and salt balance are closely linked.

Strong need to drink with intake of a lot of fluidsPolydipsia) can be the cause or consequence of increased urine excretion (Polyuria) be. People who drink a lot usually go to the bathroom more often. With a certain group of diseases, the opposite is true: a drastically increased urine excretion leads to pronounced thirst. Generic term here: Diabetes insipidus (so-called water urine clock). The focus here: Problems with the antidiuretic hormone, in short: ADH.

For diabetes (Diabetes mellitus) urination and thirst are also characteristic, but it is a completely different disorder.

Other causes for thirst and / or a lot of drinking - because this occurs even without increased thirst - include: other hormonal disorders, brain diseases, gerhin injuries and operations, drug side effects, after-effects of alcohol poisoning, psychological changes, deliberately increased fluid intake, for example in high-performance sports.


What to do? Fluid and salt losses, for example with diarrhea, vomiting and heavy sweating, must of course be compensated for. Follow the doctor's advice. For healthy adults Normally, we recommend drinking around one and a half liters per day. More precisely: The total water intake - around a third from solid foods - should be an average of 35 milliliters per kilogram of body weight. For children, the recommended amount of water to drink depends on their age; for ten year olds, for example, it should be an average of one liter a day. In addition, if someone constantly drinks a lot of fluids, something is wrong. This and / or a greatly increased or decreased urine output are always reasons for doctor to go. If you have cardiovascular or kidney disease, you should stick to the amount recommended by your doctor.

The treatment of pathological disorders with strong thirst and / or excessive amounts of drink, possibly also changes in the water and salt balance, depends on the cause and severity.

Water, the elixir of life

The sweaty round of sports is over, at the end you have to stretch your muscles, and then nothing like water for your thirsty throat. The bubbly water is twice as good: as a refreshing pleasure and replenishment for the body.

We are "Aquatiere": A good 60 percent of the normal weight of a middle-aged adult is due to body water. Since women have more body fat than men, their body water percentage is slightly lower. In children it is even 70 percent. That means: in the course of life it sinks. Nevertheless, we still consist of more than half of water.

Since the feeling of thirst also diminishes in the course of life, older people in particular, who have no health problems of the heart, kidneys or liver, should drink liquids regularly - at least one and a half liters daily, on hot days or if they sweat a lot, also significantly more (see above, section "overviewRecommended: Mineral and drinking water, unsweetened herbs and fruit teas, fruit juice spritzers.

Where are our tens of liters of body water actually located?
The body water is a functional and nutrient medium in which all important substances are dissolved - from the blood salts to the various protein particles. Over 60 percent of the body water alone benefits the body cells, the intracellular space. The cells need the fluid to work.

Another "arm" of the body water belongs to the bloodstream. The volume that washes around the body cells is even greater. The corresponding space is called the interstitium. The interstitium and blood circulation together form the important extracellular space. This is precisely what the body regulates meticulously, because this is where the vital exchange with the cells takes place. The cells themselves are only in balance if the composition of the fluid in the blood and between the cells is correct. This is the main purpose of the thirst.

Thirst: a felt signal

Even a slight increase in the concentration of particles in the blood - especially sodium ions - triggers a feeling of thirst in the brain. Table salt is our main source of sodium. Usually we take in too much of it rather than too little. After a good portion of salt in the meal, the body likes to ask for more fluids.

A lack of fluids as such can cause thirst, but this "cry for help from the extracellular space" does not penetrate as quickly and also not always if the cells themselves have not yet suffered. At least ten percent of the body's fluid has to be missing, for example in the case of severe diarrhea and fever, so that thirst really gets going - but then the situation is very serious. And in older people, who, like infants, are at an increased risk of dehydration, it is in any case not advisable to rely on thirst as a warning sign. Little and rather dark urine, a dry tongue and skin that remains as wrinkles after lifting, with a possible tendency to collapse and dizziness are clearer indications.

So thirst is not a constant. Stress or major distraction can sometimes hide the feeling of thirst. Therefore, the body still needs a more reliable regulator of water balance. This is where the neurohormone ADH comes in. Neurohormones are nerve messenger substances that are released into the blood and act on various body organs (more on this in the section "Central controllers: sensors, kidneys and hormones").

Regulating the fluid balance also means that the body separates itself from excess. Extremely practical: he gets rid of all those substances that he no longer needs. To do this, the kidneys clean the blood about 300 times a day. The end result is about one to three liters of urine. This volume, which the body excretes in portions, is also attributable to the body water. The same applies to the fluids on tissue surfaces such as the mucous membranes in the digestive tract or in the respiratory tract.

Various hormones regulate thirst

The thirst center is located in the hypothalamus (see also the picture opposite), part of the diencephalon. Certain neurohormones are also produced here. One of them is the one already mentioned ADH; it is also called adiuretin or arginine vasopressin (AVP). ADH is available in the back of the pituitary gland. If stimuli are received in the thirst center like blood "too thick" - in the sense of increasing particle concentration (osmolality) - the ADH level in the blood increases rapidly.

Under the influence of ADH, the kidneys hold back more water until we drink and the balance is established. In other words: If the ADH effect for water recovery from the urine is exhausted, the feeling of thirst is activated. First of all, however, the urine output is reduced.

ADH therefore ensures that body water is kept as constant as possible. To ensure that the "water hormone" does not react inappropriately and lead to overhydration, various opponents appear to be on the safe side. One is, for example, the atrial natriuretic factor (ANF), a special protein (peptide). It is mainly formed in the heart, more precisely in the right atrium (right atrium), reduces the release of ADH, inhibits thirst and drives away the appetite for salty foods. In the kidneys, where ANF is also active, true to its name - natriuretic means: promoting the excretion of sodium - it increases the elimination of salt and water (sodium, chloride) via the urine.

Alcohol also counteracts ADH - this time undesirable. On a humid and happy evening, the flood of spirits soon turns into a glut of urine. The next morning, the cat may also have his bill. The payment is made with a grumpy head, an empty stomach and a great deal of thirst. Eventually, the fluid that the alcohol has drawn from the body needs to be replaced. The signs of alcohol intoxication can linger for a day or two.

Causes: What makes you thirsty?

The causes of great thirst can essentially be divided into two main groups. These are conditions in which people drink more, technical term: Polydipsia. There is one caveat here, however: you don't always have a really strong thirst.

On the other hand, there is a diverse disorder called Diabetes insipidus, in which actually increased thirst is a leading symptom. This leads to a deficiency or loss of effectiveness of the "water hormone" ADH. The second key symptom is related to this: the excretion of large amounts of very dilute, very light-colored urine.

Increased drinking behavior can be brought about consciously, i.e. even without thirst.

- - marathon runners or participants in other endurance competitions are often afraid of losing too much fluids through profuse sweating. This is why they often drink far too large amounts of fluids before, during and after the run. This is risky because the rapid excess of water can lead to "blood thinning with sodium deficiency" (water poisoning and hyponatremia). Apparently, it also plays a role here that the body initially still activates the ADH under stress in order to retain body water. A possible dangerous complication is brain swelling (cerebral edema). The first signs are headache, nausea, a feeling of swelling in the hands and feet, finally confusion, in extreme cases there is a risk of seizures and coma.

! Tips: Doctors who look after marathon runners advise drinking according to their thirst, and a little more in the heat. A few hours before the competition you should drink a maximum of half a liter of liquid. It is also very important to avoid dehydration. During the marathon you should only lose weight slightly, about one and a half kilograms, at least not gain weight. Gender differences, fitness level and individual speed are important parameters (they cause different sweat production, for example). Personal advice is important.

Unconscious psychological factors also come into play with increased drinking behavior.

- - Atmental illness (Psychoses) such as schizophrenia, obsessive-compulsive disorder or the onset of anorexia nervosa, those affected tend to drink a lot of water. Increased thirst lies Not in front. The body can only handle a certain amount of fluids per day. We recommend drinking quantities of around one and a half to three liters.

Sometimes, however, polydipsia is actually an expression of a thirst that is no longer normal. It arises from disturbances in the rules of the thirst center. This can lead to diabetes insipidus (so-called dipsigenic diabetes insipidus; more on the clinical picture of diabetes insipidus below). In some cases, the same causes trigger both manifestations of the disease - polydipsia and diabetes insipidus.

- - Brain diseases, among other things, play a role here such as meningitis, for example in tuberculosis, multiple sclerosis or inflammatory systemic diseases such as sarcoid, which can spread to the brain (neurosarcoid).

- - In addition, some medications increase thirstsuch as psychotropic drugs such as lithium or anti-epileptic drugs such as carbamazepine.

The common characteristic of the disease patterns or disorders responsible here is the deficiency or loss of effectiveness of the "water hormone" ADH. Since this has to do with the brain, more precisely the hypothalamus and the pituitary gland, as well as with the kidneys, the underlying problems can largely be assigned to these two areas of the body.

Doctors thus differentiate between central diabetes insipidus, related to the pituitary gland, and diabetes insipidus due to kidney disorders (renal form). The latter is less common.

First of all, to explain: The term diabetes insipidus has nothing to do with that Diabetes, the Diabetes mellitus, to do. The only thing they have in common are the symptoms of urination (the Greek word diabetes means something like urinary dysentery) and increased thirst. In diabetes mellitus - type 1 diabetes and type 2 diabetes