Table 1 

Equations used to calculate the serum molarity prior to the calculation of the osmole gap. 

Equation Number 
Equation 


1 
Osm_{c }= 2 * Na (mEq/L) + BUN (mmol/L) + glucose (mmol/L) + ethanol (mmol/L) 
2 
Osm_{c }= 2 * Na (mEq/L) + BUN (mmol/L) + glucose (mmol/L) + 1.25 * ethanol (mmol/L) 


Equation 2 in effect inflates the ethanol concentration by 25% prior to calculating the osmole gap, as proposed by Purssell et al.[18] Osm_{c }= calculated molarity; Na = sodium; BUN = blood urea nitrogen To convert from SI units, use the following corrections: BUN/2.8 mg/dl, glucose/18.1 mg/dl, ethanol/0.217 mg/dl 

Lynd et al. BMC Emergency Medicine 2008 8:5 doi:10.1186/1471227X85 