Application of established pathophysiologic processes brings greater clarity to diagnosis and treatment of hyponatremia

Table 1 Listing the clinical features that are found in syndrome of inappropriate anti-diuretic hormone and cerebral salt wasting/renal salt wasting

Findings common to both SIADH and RSW
Association with intracranial disease
Hyponatremia
Concentrated urine
Urine sodium [Na] usually > 20 mEq/L
Non-edematous
Hypouricemia, with increased fractional excretion urate [FEurate]
Only difference between SIADH and RSW
Volume state: Normal/high in SIADH, low in RSW

Note: How the overlapping features are the most commonly encountered clinically in both syndromes and how the presence of edema can be found in CSW/RSW. SIADH: Syndrome of inappropriate anti-diuretic hormone; RSW: Renal salt wasting; FE: Fractional excretion; CSW: Cerebral salt wasting.