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Table 1 Equations used to calculate the serum molarity prior to the calculation of the osmole gap.

From: An evaluation of the osmole gap as a screening test for toxic alcohol poisoning

Equation Number

Equation

1

Osmc = 2 * Na (mEq/L) + BUN (mmol/L) + glucose (mmol/L) + ethanol (mmol/L)

2

Osmc = 2 * Na (mEq/L) + BUN (mmol/L) + glucose (mmol/L) + 1.25 * ethanol (mmol/L)

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

ISSN: 1471-227X

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