Symptoms of dehydration
| Dehydration | |
|---|---|
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| Nurses encourage a patient to drink an oral rehydration solution to reduce the combination of dehydration and hypovolemia he acquired from cholera. Cholera leads to GI loss of both excess free water (dehydration) and sodium (hence ECF volume depletion—hypovolemia). | |
| Classification and external resources | |
| Specialty | Critical care medicine |
| ICD-10 | E86 |
| ICD-9-CM | 276.51 |
| DiseasesDB | 3520 |
| MedlinePlus | 000982 |
| eMedicine | article/801012 |
| MeSH | D003681 |
In physiology, dehydration is a deficit of total body water, with an accompanying disruption of metabolic processes. It occurs when free water loss exceeds free water intake, usually due to exercise, disease, or high environmental temperature. Mild dehydration can also be caused by immersion diuresis, which may increase risk of decompression sickness in divers.
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. Death occurs at a loss of between fifteen and twenty-five percent of the body water. Mild dehydration is characterized by thirst and general discomfort and is usually resolved with oral rehydration.
Dehydration can cause hypernatremia (high levels of sodium ions in the blood) and is distinct from hypovolemia (loss of blood volume, particularly plasma).
Dehydration occurs when water intake is not enough to replace free water lost due to normal physiologic processes, including breathing, urination, and perspiration, or other causes, including diarrhea and vomiting. Dehydration can be life-threatening when severe and lead to seizures or respiratory arrest, and also carries the risk of osmotic cerebral edema if rehydration is overly rapid.
The term dehydration has sometimes been used incorrectly as a proxy for the separate, related condition hypovolemia, which specifically refers to a decrease in volume of blood plasma. The two are regulated through independent mechanisms in humans; the distinction is important in guiding treatment.
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Wikipedia