====== Urine sodium ======
[[Urine]] sodium is a measurement of the concentration of [[sodium]] in the urine.

The urine sodium is expressed as a concentration (such as millimoles per liter). The result must therefore be interpreted in the context of the degree of urine concentration present. Alternatively, the urine sodium can be standardized to the excretion of creatinine using a formula such as the fractional excretion of sodium (FENa). 

Criteria for [[cerebral salt wasting]] included [[hyponatremia]] <135 mEq/L, and [[urine]] output > 4 L in 12 hours with [[urine sodium]] >40 mEq/L.