The correlation between osmolality and specific gravity of parenteral nutrition solution.

The correlation between osmolality and specific gravity of parenteral nutrition solutions containing various concentrations of amino acid and glucose were studied. There is good correlation between osmolality and specific gravity up to 1,000 mOsmol/kg H2O and 1.050, respectively. There are strong correlations between osmolality and amino acid concentration at each concentration of glucose. An equation which can be applied for quick calculation of osmolality of the solution from amino acid and glucose concentrations is: Osmolality (mOsmol/kg H2O) = 74.36 G + 163.91 A - 36.56. The results of this study can be adopted by all physicians for quick assessment of the osmolality of the PNS before administration to patients.