Symptoms, consequences & what to do?

Quick overview: Frequently asked questions and answers

What is dehydration? Experts speak of dehydration when the body loses more fluids and/or electrolytes than it absorbs.

How do you know if you are dehydrated? Signs of dehydration include thirst, dry mouth, dark urine, decreased urine output, tiredness, dizziness, and headache. Severe dehydration may also cause confusion, rapid heartbeat, and fainting.

How do you diagnose dehydration? The skin fold test can be a clue. To do this, press the skin on the back of your hand or forearm together to form a fold. If the fold does not disappear within a few seconds, you are probably dehydrated.

At a glance:

What is dehydration?

The term dehydration is used when the body begins to dry out and therefore does not have enough water available. Particularly severe dehydration is called exsiccosis.

The word dehydration is also often used in reference to a lack of fluids. Strictly speaking, this is not correct: dehydration is a chemical reaction in which hydrogen is split off.

Function of water in the body

The human body consists mostly of water. Water is important for the most basic body functions to run properly. Water is essential for the transport of nutrients, the elimination of waste products and the functioning of the nervous system.

Various salts (electrolytes) are present in certain amounts in body water. The intracellular (in the cell) and extracellular (outside the cell) concentrations differ. Experts also speak of the intracellular space and Extracellular space.

The most important minerals are

Electrolytes are normally found mainly outside the body’s cells and only a small proportion are found inside the cells. Their distribution depends on many factors, but must be balanced.

To achieve this, electrolytes can be excreted or retained via the kidneys, digestive tract and skin. Shifts in this distribution can have serious consequences.

Dehydration: Babies and toddlers particularly at risk

Dehydration can affect people of all ages, although adults usually have fewer problems with fluid loss than babies or toddlers.

Dehydration is one of the leading causes of illness and mortality among infants worldwide because they have a higher relative basic fluid requirement and more fluid evaporates through the skin in relation to their body weight.

Dehydration is also common in older people because fluid intake is often insufficient and underlying diseases can accelerate dehydration.

Types of dehydration

There are three types of dehydration. The main difference in this definition is whether mainly water or minerals are lost.

The type of dehydration that occurs depends on many factors. In particular, the amount of electrolytes in vomit, diarrhea or sweat as well as the composition of fluids consumed can make a difference.

The following types are distinguished:

• isotone Dehydration: In this form of dehydration, the concentration of sodium ions in the blood is normal and water and minerals (especially sodium) are lost in equal proportions. Reasons include not drinking enough, diarrhea or vomiting.

• hypertone Dehydration: In the hypertonic form, there is a relatively greater loss of water than of mineral salts. The body loses the water but retains the minerals. As a result, the concentration of electrolytes, especially sodium ions, increases. Causes can be diabetes insipidus, fever or heavy sweating.

• hypotone Dehydration: If the body excretes too many minerals, there are relatively few electrolytes, especially sodium, in the water available. This is then referred to as hypotonic dehydration. This can occur, for example, if dehydration occurs by drinking distilled water or other liquids without the necessary amount of dissolved minerals.

Symptoms: How does dehydration manifest itself?

The onset of dehydration is usually noticeable early on, but is perceived very individually by each person. Even mild dehydration can cause initial symptoms, which increase with the severity of the stages.

Symptoms of mild dehydration (three to five percent fluid loss)

Symptoms of moderate dehydration (six to eight percent fluid loss)

• sunken eyes with dark circles
• very dry skin and mucous membranes
• severely reduced urine excretion (oliguria)
• Heart palpitations (tachycardia)
• bad breath
• inertia

Symptoms of severe dehydration (nine to twelve percent fluid loss)

• low blood pressure (hypotension)
• Persistent skin folds, for example on the back of the hand
• reduced skin blood flow
• confusion
• Muscle cramps
• Symptoms of shock (more than twelve percent fluid loss): dizziness, circulatory weakness, impaired consciousness up to coma

In addition to circulatory shock, severe dehydration of the body can lead to kidney failure, increased risk of infection and thrombosis (blood clots).

Dehydration: What are the possible causes

Dehydration occurs when fluid intake is too low, too much fluid is lost, or a combination of both.

There are numerous possible reasons for dehydration. Typical causes include:

• insufficient fluid intake due to heavy sweating or, especially in the elderly, due to a lack of thirst

• Diarrhea

• Vomit

• Fever

• Blood loss

• Burns

• Disorders of renal function

• Addison’s disease (adrenal hypofunction)

• Diabetes mellitus (diabetes)

• Diabetes insipidus (Wasserruhr)

• Therapy with diuretics

How is dehydration diagnosed?

The diagnosis of dehydration is mainly made after a detailed medical history and physical examination.

During the discussion with the medical staff, acute or recent complaints such as diarrhea, vomiting or feverish infectious diseases are asked about, and drinking habits and possible triggering medications are checked.

Furthermore, headaches, clouding of consciousness or known chronic illnesses indicate the presence of dehydration.

The subsequent physical examination looks for typical signs of dehydration. Blood and urine can then be examined in the laboratory. This provides information about possible changes in electrolyte balance and allows statements to be made about kidney function.

If no obvious cause for dehydration can be found, the doctor must investigate after acute treatment whether the dehydration was caused by an existing illness.

Which therapy helps with dehydration?

The first step in the case of dehydration is to compensate for fluid loss and restore electrolyte balance to normal.

If the lack of fluids is only mild or moderate, this can be achieved by drinking. In particular, mineral-rich drinks such as

• Mineral water,
• Fruit and herbal tea,
• Juice spritzer or
• broth

are suitable for compensating for the loss. It may be useful to administer electrolyte mixtures in addition.

When infusions are necessary

If the degree of dehydration is more severe or if those affected are unable to drink enough, infusions may be necessary. In normal cases, the infusions are administered intravenously (into the vein). In home and elderly care, subcutaneous infusions (under the skin) are also used.

The infusion solutions are put together based on the results of the blood and urine tests. In addition to water, they can also contain electrolytes or glucose, depending on whether the mineral balance is disturbed or not.

Infusions of two to four liters are usually sufficient, but in some cases larger quantities are required.

In addition to the direct treatment of dehydration, it is necessary to treat underlying diseases such as infections, diabetes mellitus or kidney disease.

How can dehydration be prevented?

To prevent dehydration or to treat a mild form yourself, drinking enough fluids is essential.

The German Nutrition Society (DGE) recommends that adults drink about one and a half liters of liquid daily and consume another liter through a balanced diet with sufficient fruit and vegetables.

The most important measure is to adapt the amount you drink and your drinking habits to the external conditions and, for example, drink more when it is very hot or you are doing a lot of physical exertion. This also applies when you are only slightly thirsty. If you are sweating heavily, the drinks should contain electrolytes.

Especially in children and the elderly, but also in adults, one should pay attention to the signs of incipient dehydration and, if necessary, increase the amount of fluids independently.