Diagnostic Values | SIADH | CSW |
Serum Na level, mEq/L [11] | Hyponatremia (<135) | Hyponatremia (<135) |
Serum Osmolality, mOsm/kg [26] | <275 (low) | <275 (low) |
Urinary Na level, mEq/L [26] | Normal or elevated (>30) | Elevated (>30) |
Urinary Osmolality, mOsm/kg [26] | Elevated (>100) | Elevated (>100) |
Urinary Specific Gravity [18] | >1.010 (concentrated) | >1.010 (concentrated) |
Urine Output [18] | Decreased (500 mL/24 h) | Decreased |
Fluid Volume Status [13] | Euvolemic | Hypovolemic |
Central Venous Pressure [2] [26] | Normal, or increased (>6 cm water) | Decreased (<6 cm water) |
Fractional Excretion Of Uric Acid [14] [26] | >12%, then decreases as Na returns to baseline | >12%, and stays elevated as Na returns to baseline |
Fractional Excretion of Phosphate [32] | Normal (<10%) | Elevated (>20%) |