Estimating Serum Levels of Isopropanol and Acetone from the Osmolal Gap

Isopropanol (2-propanol, isopropyl alcohol) and acetone are osmotically active and can be estimated from the osmolal gap.

Isopropanol = (CH3)2 – CHOH with molecular weight 60.10, with density 0.79 g/mL.

Acetone = CH3 – CO – CH3 with molecular weight 58.08

Acetone is often formed during the metabolism of isopropyl alcohol.

	1 mg/dL in serum will affect osmolality by	1 mOsm per kg H2O reflects serum levels
acetone	0.18 mOsm per kg H2O	5.5 mg/dL
isopropanol	0.17 mOsm per kg H2O	5.9 mg/dL

where:

• 1 mOsm per kg H2O roughly approximates a serum level of 1 mmol/L, or (molecular weight) / 10 mg/dL.

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