Publication | Closed Access
Calculated vs measured plasma osmolalities revisited.
90
Citations
0
References
1984
Year
Electrolyte DisorderEngineeringMeasurementManual CalculationsPlasma PhysicsPlasma MedicineRenal FunctionCalibrationPlasma SimulationPlasma TheoryBioanalysisElectrolyte DisturbanceBiostatisticsAnalytical ChemistryPlasma ConfinementClinical ChemistryInstrumentationCalculation ErrorsPlasma DiagnosticsPlasma ConcentrationsPlasma ApplicationUrologyPlasma OsmolalitiesPhysiologyMass SpectrometryMetabolismMedicineNephrology
The osmolalities of 100 plasma samples were measured and compared with the osmolalities calculated from the plasma concentrations (mmol/L) of sodium, potassium, glucose, and urea by several different formulae. The formula recommended by Dorwart and Chalmers (Clin Chem 21: 190, 1975) gave inferior results to those obtained with our "most accurate" formula: osmolality = 1.89 Na + 1.38 K + 1.03 urea + 1.08 glucose + 7.45. We recommend using this formula for calculation of osmolality on equipment linked to a computer. However, for simplicity, and to reduce the possibility of calculation errors, the following formula can be used for manual calculations: osmolality = 1.86 (Na + K) + glucose + urea + 10.