Metabolic

Serum osmolality and osmolar gap

Detect unmeasured osmoles such as toxic alcohols.

Version Standard

Inputs

Sodium(mmol/L)

Urea(mmol/L)

Glucose(mmol/L)

Measured osmolality(mOsm/kg)

Osmolar gap (mOsm/kg)

Normal — significant unmeasured osmoles are unlikely.

Calculated osmolality 290 mOsm/kg

Formula

Calculated osmolality = 2×Na + urea + glucose (mmol/L); gap = measured − calculated

DrZep editorial · 2026

Demo content. Educational decision support only. Verify every dose, citation and recommendation against your national formulary and the primary source before clinical use.