Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1224 page)

•   Greater than 14 years: 27–287 mmol/day

   Random urine

   Male: 23–229 mmol/g creatinine

   Female: 26–297 mmol/g creatinine

   Use

   Volume depletion: to determine the route of sodium loss. Low urinary sodium indicates extrarenal loss, and high value indicates renal salt wasting or adrenal insufficiency.

   Differential diagnosis of acute renal failure: high values are consistent with acute tubular necrosis.

   In hyponatremia, low urinary sodium indicates avid renal sodium retention, which may be attributable to either severe volume depletion or sodium-retaining states seen in cirrhosis, the nephrotic syndrome, and CHF. When hyponatremia is associated with urinary sodium excretion that equals or exceeds the dietary sodium intake, it is likely that SIADH is present.

   Interpretation

Increased In

   Dehydration

   Salicylate intoxication

   Adrenocortical insufficiency

   Diabetic acidosis

   Mercurial and thiazide diuretic administration