Table 2.
Effect of Sample Volume on Whole Blood and Plasma Osmolality Measurements (mmol/kg)
| 20 μl Sample volume | 250 μl Sample volume | |||
|---|---|---|---|---|
| Volunteer no. | Whole blood | Plasma | Whole blood | Plasma |
| 1 | 304 | 290 | 288 | 287 |
| 2 | 301 | 296 | 293 | 290 |
| 3 | 296 | 287 | 286 | 284 |
| 4 | 310 | 293 | 292 | 290 |
| 5 | 299 | 289 | 285 | 284 |
| 6 | 303 | 289 | 291 | 288 |
| 7 | 306 | 293 | 290 | 289 |
| 8 | 297 | 284 | 287 | 281 |
| 9 | 307 | 290 | 290 | 287 |
| 10 | 301 | 294 | 290 | 287 |
| Mean ± SD | 302 ± 5 | 291 ± 4 | 289 ± 3 | 287 ± 3 |
All means were statistically different from each other (P < 0.01), but differences ≤4 mmol/kg were considered marginal (40).