Internal Medicine · Emergency Medicine · Nephrology

Calculated Serum Osmolality (2×[Na+K]) calculator

Enter the published formula inputs below to calculate and interpret this score.

Clinical inputs

Serum sodium (mmol/L)

Serum potassium (mmol/L)

Serum glucose (mg/dL)

Blood urea nitrogen (mg/dL)

Result

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Formula inputs

Serum sodium (mmol/L)Accepted range: 100 to 180
Serum potassium (mmol/L)Accepted range: 1 to 10
Serum glucose (mg/dL)Accepted range: 0 to 1200
Blood urea nitrogen (mg/dL)Accepted range: 0 to 200

Primary source

Bhagat MC et al. Calculated vs measured plasma osmolalities revisited. Clin Chem. DOI: 10.1093/clinchem/30.10.1703. PMID: 6481130. Scope: calculated serum osmolality (mOsm/kg) = 2 × (sodium + potassium in mmol/L) + glucose/18 + BUN/2.8 when glucose and BUN are in mg/dL. (1984)

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