What it means
Osmolality tells how concentrated a fluid is: how many particles, such as sodium, glucose and urea, are dissolved in each kilogram of water. Serum osmolality is written in mOsm/kg. A high value means the blood is too concentrated, as in dehydration or very high glucose; a low value means it is too dilute, as in water overload.
At a glance
| Normal range | Serum osmolality 275–295 mOsm/kg [275–295 mmol/kg] |
|---|---|
| Also written | mOsm/kg, milliosmoles per kilogram |
Related terms
dehydration
A state in which the body has lost more water than it has taken in.
electrolyte
A mineral that carries an electric charge when dissolved in body fluids, such as sodium, potassium, calcium and chloride.
sodium
A mineral in the blood that controls how water moves in the body and helps nerves and muscles work.