Osmolaalinen

Osmolaalinen is an adjective used in chemistry and physiology to describe properties related to osmolality—the concentration of osmotically active particles per kilogram of solvent. The osmolality of a solution is measured in osmoles per kilogram (Osm/kg), commonly expressed in milliosmoles per kilogram (mOsm/kg). Osmolarity is closely related but defined as osmoles per liter of solution; in dilute aqueous solutions, osmolarity approximates osmolality, but the two are distinct quantities.

Osmolaalinen describes how concentrated a solution is in terms of its osmotically active particles. It is influenced by solutes such as ions (sodium, chloride, bicarbonate), glucose, urea, and alcohols. In clinical practice, plasma osmolality is typically about 275–295 mOsm/kg. It can be measured directly with an osmometer or estimated from solute concentrations, using a common formula: Osmolality ≈ 2 × Na+ + Glucose/18 + BUN/2.8 (mOsm/kg). Additional solutes like ethanol add to osmolality when present.

Osmolaalinen considerations are important in diagnosing and managing fluid balance disorders, dehydration, kidney and endocrine diseases, and poisoning states. The concept is fundamental to understanding osmosis, diffusion, and the movement of water across membranes, since osmolality drives the net movement of water.

See also: osmolality, osmolarity, osmosis.