Osmolality
| Formula / Notation | Osm = Σ(n × C) |
|---|---|
| Also Known As | Osmolarity (related), effective osmolarity, tonicity, serum osmolality |
What is Osmolality?
Osmolality is a measure of the osmotic concentration of a solution expressed as the number of osmoles of solute per kilogram of solvent (Osm/kg or mOsm/kg). It is distinct from osmolarity (per liter of solution). Osmolality is measured by freezing point depression and is the clinically preferred measure of body fluid concentration. Normal serum osmolality is 280–295 mOsm/kg.
Formula & Notation
Other Names / Synonyms: Osmolarity (related), effective osmolarity, tonicity, serum osmolality
Properties & Characteristics
Uses & Applications
Safety Information
Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.
Key Facts
Frequently Asked Questions
Osmolality is a measure of the osmotic concentration of a solution expressed as the number of osmoles of solute per kilogram of solvent (Osm/kg or mOsm/kg). It is distinct from osmolarity (per liter of solution). Osmolality is measured by freezing point depression and is the clinically preferred measure of body fluid concentration. Normal serum osmolality is 280–295 mOsm/kg.
Clinical medicine (assessing dehydration, electrolyte disorders). Pharmaceutical formulation of IV fluids. Renal function assessment. Dialysis fluid preparation. Intravenous nutrition. Cryoprotection solutions. Sports medicine (hydration assessment).
Clinical measurement of serum osmolality — sampling requires phlebotomy. Hyperosmolar states: dehydration, hyperglycemia — medical emergency. Hypoosmolar states: overhydration, hyponatremia — cerebral edema risk.
The formula or notation for Osmolality is: Osm = Σ(n × C)