calculated serum osmolality

cal·cu·lat·ed se·rum os·mo·lal·i·ty

the calculation of serum osmolality from serum sodium, glucose, and urea nitrogen values by a variety of formulae, the most common of which is: 1.86 × [Na] (mmol/L + glucose (mg/dL)/18 + BUN (mg/dL)/2.8.