Calculated serum osmolality can lead to a systematic bias compared to direct measurement.

@article{Vialet2005CalculatedSO,
  title={Calculated serum osmolality can lead to a systematic bias compared to direct measurement.},
  author={Renaud Vialet and M. Di Leone and Jacques Alban{\`e}se and Claude Martin},
  journal={Journal of neurosurgical anesthesiology},
  year={2005},
  volume={17 2},
  pages={106-9}
}
The reference method to measure serum osmolality (Mosm) is the delta cryoscopic method. However, the technology may not be available. Clinicians therefore must calculate osmolality (Cosm) as the sum of concentrations of selected principal solutes such as sodium, potassium, urea, and glucose. To evaluate the validity of Cosm in patients in hyperosmolar state we compared Cosm to Mosm. Twenty-two ICU patients treated by infusion of hypertonic solutes for intracranial hypertension following head… CONTINUE READING