Osmolality increases when you are dehydrated and decreases when you have too much fluid in your blood. Your body has a unique way to control osmolality. When osmolality increases, it triggers your body to make antidiuretic hormone (ADH).

What causes high plasma osmolarity?

Abnormally high blood osmolality can result from a variety of conditions, including: dehydration. diabetes insipidus. head trauma.

What happens if blood osmolality is too high?

In healthy people, when osmolality in the blood becomes high, the body releases antidiuretic hormone (ADH). This hormone causes the kidneys to reabsorb water. This results in more concentrated urine. The reabsorbed water dilutes the blood.