Table 2.
Calculated osmolality (CO) and osmolal gap (OG).*
| Formula | CO | OG | ||
|---|---|---|---|---|
| Mean | SD | Mean | SD | |
| 2(Na) + Glu + 0.5(Urea) | 291 | 3.2 | 1.8 | 4.7 |
| 2(Na) + 10 | 293 | 3.1 | −0.9 | 4.5 |
| 0.985[2 (Na + K) + Glu + 0.5(Urea)] | 294 | 3.2 | −1.4 | 4.8 |
| 1.89(Na) +1.38(K) + 1.08(Glu) + 1.03(Urea) + 7.45 | 291 | 3.1 | 1.8 | 4.7 |
| 2(Na) + 1.15(Glu) + Urea | 294 | 3.2 | −1.3 | 4.7 |
| 2(Na) + Glu + Urea | 293 | 3.2 | −0.6 | 4.8 |
*
Calculated osmolality (CO) formulae that gave mean osmolal gap (OG) values within +/−2 mOsm/kg of zero when applied to common chemistry results on serum pools from two healthy individuals reported by 35 laboratories in the RCPAQAP Liquid Serum Chemistry Program 2013. Unit for osmolality is mOsm/kg.