The osmotic effect of soluteconcentrationplays a key role in homeostasis. Solute concentrationdetermines tolarge degree the intracellular and extracellularvolume andtonicity. Many poisons, medications and diseases effectthe balancebetween the intracellular and extracellular fluidvolumes.
A serum osmolality test measures the amount of chemicalsdissolvedin the liquid part (serum) of the blood. Serum osmolalitycan becalculated by measuring the amounts of sodium, glucose, andbloodurea nitrogen (BUN) in the blood.