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Dehydration
Make it clearer
Dehydration is what happens when the body loses more fluid than it takes in. The result is that total body water, all the water inside the body, goes down. It is like a bucket losing water faster than it is refilled: the level keeps dropping.
The body has mechanisms to counter it. Some of them track plasma osmolality, which is how concentrated the liquid part of the blood is. When osmolality rises, the hypothalamus, an area of the brain, triggers thirst. And the posterior pituitary, a small gland that hangs below the brain, releases antidiuretic hormone: with it, the kidneys reclaim more water and less urine comes out.
Dehydration can be mild or severe enough to be life-threatening. Early on, you may notice more thirst, a dry mouth, weakness and less urine.
In brief
Dehydration occurs when fluid loss exceeds intake and total body water falls.
A bucket losing more water than it takes in.
Among the body's defenses, when plasma osmolality rises, the hypothalamus triggers thirst and the posterior pituitary secretes antidiuretic hormone, which increases water reabsorption in the kidney and reduces urine output.
It can range from mild to severe enough to be life-threatening; early symptoms may include increased thirst, dry mouth, weakness and decreased urination.
Sources (2)
- National Center for Biotechnology Information, StatPearls PublishingAdult Dehydration, StatPearlsPublished
- MedlinePlus, U.S. National Library of MedicineDehydration, MedlinePlusPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
Updated