The osmolal gap is the difference between the measured osmolality and the calculated osmolality. A significant osmolal gap can suggest the presence of toxins such as methanol, ethylene glycol, or other volatile substances. The calculated osmolality is typically derived from the concentrations of sodium, glucose, and urea using the formula: Calculated osmolality = 2 Ã [Na+] + [Glucose]/18 + [BUN]/2.8 An elevated osmolal gap often necessitates further investigation to identify and treat the underlying toxic exposure.
