Plasma osmolality

Plasma osmolality

Normal human reference range of osmolality in plasma is about 275-299 milli-osmoles per kilogram.

To calculate plasma osmolarity use the following equation :

  • = 2 x Na+ + Glucose + BUN
    18 2.8

where [Glucose] and [BUN] are measured in mg/dL.

Simplifications are sometimes used:

  • = 2[Na+] + [Glucose]/20 + BUN/3 - 2