Table 2.
Hormonal, electrolyte, hematocrit, and total protein changes during hypertonic saline infusion and water loadinga
| Variables | Hypertonic Saline Infusion
|
Water Loading
|
||
|---|---|---|---|---|
| Time 0 | Time 120 | Time 0 | Time 240 | |
| Plasma sodium (mmol/L; mean ± SD) | 138.8 ± 0.9 | 147.4 ± 0.9 | 137.0 ± 1.2 | 136.5 ± 1.9 |
| Hematocrit (%; mean ± SD) | 42.9 ± 2.4 | 38.6 ± 3.0 | 43.4 ± 2.1 | 44.7 ± 3.0 |
| Total proteins (g/L; mean ± SD) | 69.2 ± 2.7 | 59.4 ± 2.7 | 69.0 ± 3.3 | 70.5 ± 2.4 |
| Plasma active renin (pg/ml; mean ± SD) | 35.8 ± 8.4 | 17.4 ± 3.2 | 22.0 ± 6.4 | 24.0 ± 8.0b |
| Plasma aldosterone (pg/ml; median [IQR]) | 88 (79 to 145) | 50 (33 to 52) | 114 (84 to 117) | 77 (69 to 120)b |
| Cumulative Na input (mmol; mean ± SD)c | – | 465 ± 36 | – | 0 |
| Cumulative Na output (mmol; mean ± SD)c | – | 53 ± 28 | – | 29 ± 13 |
| Cumulative water input (ml; mean ± SD)c | – | 550 ± 37 | – | 1546 ± 68 |
| Cumulative water output (ml; mean ± SD)c | – | 255 ± 106 | – | 1554 ± 327 |
| ECFV (L; mean ± SD) | 16.0 ± 0.9 | 18.8 ± 1.1 | 16.1 ± 0.4 | 15.9 ± 0.3 |
| ECFV changes (%; mean ± SD)d | – | 17.4 ± 1.6 | – | −1.3 ± 0.6 |
The hypertonic saline infusion caused a significant and marked decrease in hematocrit (P = 0.0017), total protein concentration (P = 0.0003), and plasma active renin (P = 0.0019) and aldosterone (P = 0.0198) concentrations. Water loading had no significant effect on hematocrit or total protein, plasma active renin, and aldosterone concentrations.
Plasma active renin and aldosterone were measured at time 180.
Cumulative Na and water input/output are cumulative over 120 min for the hypertonic saline infusion or over 240 min for the water loading test.
ECFV and ECFV changes (%) were estimated according to the following formula: Variation in ECFV (% of initial volume) = [(final P[Na+])/net Na+ balance]/initial ECFV × 100, with initial ECFV (L) = [(8116.6 × BSA) − 28.2]/1000, where BSA is body surface area and net Na+ balance (mmol/l) = Na+ input − Na+ output.