Dehydration
Dehydration refers to a deficit of total body water, with an accompanying disruption of metabolic processes. Dehydration is also a cause for hypernatremia. The term dehydration must be distinguished from hypovolemia (loss of blood volume, particularly plasma).
Dehydration occurs when free water loss exceeds free water intake, usually due to exercise or disease. Most people can tolerate a three to four percent decrease in total body water without difficulty or adverse health effects. A five to eight percent decrease can cause fatigue and dizziness. Loss of over ten percent of total body water can cause physical and mental deterioration, accompanied by severe thirst. A decrease of more than fifteen to twenty-five percent of the body water is invariably fatal. Mild dehydration is characterized by thirst and general discomfort and is usually resolved with oral rehydration.
Definition