What is dehydration?

Dehydration is a decrease in your body's fluid levels, which occurs when you lose more fluid than you take in. Without the appropriate levels of fluids and salts, normal bodily functions can be affected. When you lose fluids they need to be replaced to ensure dehydration does not worsen.

Dehydration in children is common as they have a higher turnover of fluids than adults, therefore they need proportionally larger volumes of water to maintain a healthy fluid level. Dehydration in children can be caused by excessive physical activity, hot weather, illness, vomiting, diarrhoea, fever and extreme sweating.

It is best to prevent dehydration from occurring in the first place; this can be done by teaching children about the importance of hydration and encouraging them to drink plenty of water during hot weather and exercise.

Causes

Dehydration in children occurs when fluids are lost from the body faster than they are replaced. This can occur quickly to babies and young children in hot weather, particularly if there is increased sweating and a reduced intake of fluids. This can also occur if children spend too much time in the direct sun, are in a hot room or a hot car. Illnesses that involve diarrhoea, vomiting and fever are a common cause, as is excessive physical activity.

Diarrhoea, vomiting and fever

Diarrhoea that occurs suddenly and severely can lead to a large loss of fluids and electrolytes in a short period of time. This may be caused by a viral or bacterial infection, or food sensitivity. If vomiting also occurs at this time, even more fluids can be lost. A fever, which causes sweating, can also worsen dehydration.

Excessive physical activity

Excessive physical activity can lead to dehydration. Many children like to play sport, which increases sweating. If they do not keep up their fluids during physical activity, dehydration can occur. Dehydration occurs more often in children due to their low body weight and because they may not identify the signs of dehydration.

Electrolytes

Substances that form ions when dissolved in water. These include potassium and sodium minerals that are necessary for normal functioning of the body and all its cells.

Infection

Entry into the body of microorganisms that can reproduce and cause disease.

Risk factors

Any child can become dehydrated, however there are increased risks for children who:

  • Have a loss of appetite due to an acute illness or experience diarrhoea, vomiting and fever;
  • Have diabetes;
  • Live in warmer climates, and;
  • Play sport, particularly in the sun.

Diabetes

A metabolic disorder that is caused by problems with insulin secretion and regulation and which is characterised by high blood sugar levels. Also known as diabetes mellitus.

Types

Dehydration in children can be categorised into mild, moderate and severe stages. These are based on the loss of body weight. Mild dehydration occurs when there is a loss of body weight between 5-6%. Moderate dehydration occurs when there is a loss of body weight between 7-10%. Severe dehydration occurs when there is a loss of body weight between 10-15%.

Signs and symptoms

The signs and symptoms associated with each stage can vary. 

Mild dehydration

In mild dehydration, the only signs and symptoms may be thirst and restlessness. 

Moderate dehydration

Some symptoms of moderate dehydration in children can include restlessness, irritability, inactivity, dry mouth, sunken eyes, and reduced urine output (less wet nappies in infants).

Severe dehydration

Some symptoms of severe dehydration in children can include extreme thirst, extremely dry mouth, cracked lips, little or no urine output, confusion and unconsciousness, rapid breathing and heart rate, and low blood pressure.

Blood pressure

The pressure the blood places on the walls of the arteries, largely mirroring the contraction of the heart, and consisting of two readings. The higher reading is systolic blood pressure, when the heart contracts, and the lower is diastolic blood pressure, when the heart is relaxed.

Methods for diagnosis

A diagnosis of dehydration can usually be based upon a child's physical appearance. A physical examination by your doctor can reveal a lack of elasticity in the skin, sunken eyes, a rapid heart rate, and low blood pressure. To identify the severity of dehydration, blood tests can be performed to check electrolyte levels. Urine tests can also be performed to check the concentration of urine.

Blood pressure

The pressure the blood places on the walls of the arteries, largely mirroring the contraction of the heart, and consisting of two readings. The higher reading is systolic blood pressure, when the heart contracts, and the lower is diastolic blood pressure, when the heart is relaxed.

Electrolyte

Substances that form ions when dissolved in water. These include potassium and sodium minerals that are necessary for normal functioning of the body and all its cells.

Types of treatment

It is important to begin treatment of dehydration in children as soon as it is recognised. Treatment focuses on replacing electrolytes and fluids that have been lost and is based on the severity of the condition.

Mild dehydration

In children with mild dehydration, fluid losses can be replaced through drinking fluids until hydration is reached. This can be over a period of 3-4 hours. After hydration, it is also important for children to eat to replace any lost calories. If the dehydration has occurred in a baby, breastfeeding can be continued to rehydrate. If children are suffering from vomiting and diarrhoea, an oral rehydration solution (ORS) containing sugar (glucose) and electrolytes (sodium, potassium and chloride) can be given. 

Moderate and severe dehydration.

Children suffering from moderate and severe dehydration will require treatment at a medical facility. Fluids are generally given intravenously (IV). This involves inserting a small needle into a vein, usually in the arm and administering fluids. This method helps to quicken the recovery time.

Calories

A measure of the energy in foods and drink, and the energy that our bodies burn. Calories are imperial units.

Electrolytes

Substances that form ions when dissolved in water. These include potassium and sodium minerals that are necessary for normal functioning of the body and all its cells.

Potential complications

Children with dehydration may experience complications if dehydration reaches a severe stage. One complication that can occur is called hypovolemic shock, where there is insufficient fluids for the heart to adequately pump blood around the body. This complication is characterised by pale, clammy skin that is cool to touch, a rapid heartbeat and shallow breathing. Blood pressure can also drop to an unreadable level. Unconsciousness and death will follow if severe dehydration is not treated. If a child is experiencing severe dehydration, emergency services must be called.

Blood pressure

The pressure the blood places on the walls of the arteries, largely mirroring the contraction of the heart, and consisting of two readings. The higher reading is systolic blood pressure, when the heart contracts, and the lower is diastolic blood pressure, when the heart is relaxed.

Prognosis

Dehydration in children is a treatable condition. It is important to identify the symptoms early and begin treatment as soon as possible. Treatment is focused on replenishing the electrolytes and fluid that have been lost during dehydration. 

Electrolytes

Substances that form ions when dissolved in water. These include potassium and sodium minerals that are necessary for normal functioning of the body and all its cells.

Prevention

Dehydration in children is a preventable condition. A healthy fluid balance can be maintained in children if they drink water or other fluids before they feel thirsty. It is also important for them to drink extra fluids before physical activity or during hot weather. A good rule is for children to have 6-8 cups of fluid each day, preferably water. Fruits and vegetables have a very high water content, so adopting healthy eating is a great way to stay hydrated. It is also possible to reduce the risks of dehydration by replacing fluids lost during diarrhoea and vomiting as they occur.

Bottled water.Maintaining regular fluid intake will prevent dehydration.