Dehydration is an excessive loss of water from tissues, often accompanied by an alteration in the balance of electrolytes such as sodium, potassium and chlorine. This clinical condition can occur whenever the fluid intake is less than the leakage. In early stages dehydration is asymptomatic; mild to moderate dehydration may be accompanied by symptoms such as thirst, fatigue, muscle cramps, chills and headache. Severe dehydration may be accompanied by more severe symptoms such as confusion, hypotension, loss of consciousness, shock to death.
The human body is made up of 60-70% water; for this reason it is necessary to continuously ensure a sufficient supply of water. Water is mostly consumed through the diet, i.e. through the intake of food and drink. It is absorbed at the intestinal level and transported throughout the body, where it is distributed within the cells, in the spaces between the cells and tissues, in the lymphatic system, in the mucous membranes and in the liquid part of the blood contained in the veins and arteries. If necessary, fluids can be transported from one compartment to another.
Maintaining water balance within the body is a complex process. The kidneys are part of a complex feedback system responsible for maintaining or eliminating water through the concentration or dilution of urine or the control of sodium absorption. Sodium and other electrolytes – potassium, chlorine and bicarbonate – help regulate the water balance at the cellular level by maintaining the acid-base balance.
This feedback system is critical to maintaining water balance. The body’s receptors detect and respond to the increase and decrease in the amount of water by dissolving substances in the bloodstream. The increase in the concentration of dissolved particles (osmolality), due to the decrease in water or the actual increase in particles, stimulates the secretion of the antidiuretic hormone (ADH) by the hypothalamus (specialized gland of the central nervous system). This hormone acts on the kidneys by stimulating water reabsorption. The water is also moved from the cells to the bloodstream in order to keep blood pressure and volume within physiological levels. If normal osmolality levels are not restored, the tissues are dehydrated and damaged. Decreased water levels stimulate the central nervous system to transmit the feeling of thirst, causing the person to drink water. All of these mechanisms contribute to maintaining normal water balance. To not forget to drink water int time you can use hydrate app.
The loss of fluids/liquids faster than their intake leads to dehydration. This clinical condition may be a consequence of vomiting, diarrhoea, sweating, use of diuretics and/or insufficient fluid intake. This situation may also be worsened by excessive sodium loss (hyponatriemia) or excess (hypernatremia) in relation to the amount of water. Prolonged dehydration can lead to shock and organ damage, particularly to the brain, resulting in a state of confusion, coma to death.
Anyone can experience dehydration, but this clinical condition tends to be more severe in young people, the elderly and people with major comorbidities or compromised immune system. Babies and children may have difficulty communicating their need to drink. Children have a faster metabolism than adults, as well as a higher percentage of water, so children’s need for water is greater. In children, sweat, vomiting and diarrhoea are frequently associated with rapid fluid loss; for this reason, gastrointestinal diseases are a serious health threat in children. According to the World Health Organization, diarrhoeal disease is the second leading cause of death in children under the age of five.
Dehydration is also a major problem in the elderly, among whom it is a chronic condition in about 20% of cases.