Calculator: Serum osmolal gap (conventional units)*

Calculator: Serum osmolal gap (conventional units)^*

Input

Serum Na		mEq/L
Serum glucose
Serum BUN
Serum ethanol
Measured Osm

Results

Important: Inputs must be complete to perform calculation.


Calculated Osm
Osmolal gap

Decimal precision

Notes

BUN: blood urea nitrogen; Osm: osmolality.
The plasma osmolality is determined by the concentration of the different solutes in the plasma.
In normal subjects, sodium salts (chloride and bicarbonate), glucose, and urea are the primary circulating solutes.
The calculated plasma osmolality normally is between 270 and 290 mOsm/kg H₂O and the Osmolal gap is normally <10 mOsm/kg H₂O. You can calculate the Osmolal gap from the formulas depicted.
In this calculator, mcg is the abbreviation for micrograms.
* This calculator uses conventional units (also known as US units and gravimetric units) as the default for inputs. Do not use this calculator if you are using SI units (Système international d'unités); please refer instead to the SI units version of this calculator.

Equations used

Calculated_Osm = (Serum_Na * 2) + (Serum_glucose / 18) + (Serum_BUN / 2.8) + (Serum_ethanol / 3.7)

Osmolal_gap = Measured_Osm - Calculated_Osm

References

Only digits 0 to 9 and a single decimal point (".") are acceptable as numeric inputs. Attempted input of other characters into a numeric field may lead to an incorrect result.

Information on this page may not appear correctly if printed.

All information contained in and produced by the EBMcalc system is provided for educational purposes only. This information should not be used for the diagnosis or treatment of any health problem or disease. THIS INFORMATION IS NOT INTENDED TO REPLACE CLINICAL JUDGMENT OR GUIDE INDIVIDUAL PATIENT CARE IN ANY MANNER. Click here for full notice and disclaimer.

Topic 13498 Version 13.0