What is osmolarity of body fluids?

1 Answer
May 22, 2014

The normal osmolarity of body fluids is 285-295 mOsm/L.

Osmolarity is a measure of the body's water-electrolyte balance.

When osmolality in the blood of healthy people becomes high, the body releases antidiuretic hormone, ADH.

This hormone causes the kidneys to reabsorb water. The reabsorbed water dilutes the blood. This allows blood osmolality to fall back to normal.


Low blood osmolarity suppresses ADH. This reduces the amount of water the kidneys reabsorb. The body passes dilute urine to get rid of the excess water. The blood osmolarity increases to normal.