Urine Sodium 

Updated: Dec 05, 2013
  • Author: Fazia Mir, MD; Chief Editor: Eric B Staros, MD  more...
  • Print

Reference Range

Measurement of the urine sodium concentration is vital in determining the integrity of tubular reabsorptive function. Low urine sodium concentration thus indicates not only intact reabsorptive function but also the presence of a stimulus to conserve sodium, whereas a high urine sodium concentration may signify other salt wasting etiologies. It is usually ordered when we need to distinguish between various forms of renal failure and classifying hyponatremia. [1]

The reference range for urine sodium is 40-220 mEq/L/24 hours.

Next:

Interpretation

Conditions associated with increased urine sodium include the following [2] :

  • Excessive dietary salt
  • Diuretic therapy
  • Salt-wasting nephropathy
  • Acute tubular necrosis
  • Analgesic abuse–induced interstitial nephritis
  • Syndrome of inappropriate antidiuretic hormone hypersecretion (SIADH)
  • Vomiting
  • Hypothyroidism
  • Postobstructive diuresis
  • Hepatic failure
  • Congestive heart failure

Conditions associated with decreased urine sodium include the following:

Previous
Next:

Collection and Panels

Specifics for collection and panels are as follows:

  • Specimen type: Urine
  • Container: Urine collection container
  • Collection method: 24-hour urine collection
  • Specimen volume: 5 mL
  • Other instructions: Add 25 mL of 50% acetic acid to collection container as preservative before starting collection

Related tests include the following:

  • Serum sodium
  • Serum electrolytes
  • Urine osmolality
Previous
Next:

Background

Description

Measurement of the urine sodium concentration is vital in determining the integrity of tubular reabsorptive function. Low urine sodium concentration thus indicates not only intact reabsorptive function but also the presence of a stimulus to conserve sodium, whereas a high urine sodium concentration may signify other salt wasting etiologies. It is usually ordered when we need to distinguish between various forms of renal failure and classifying hyponatremia. [1]

Indications/Applications

Indications for testing of urine sodium include the following:

Considerations

Drugs that can increase urine sodium include the following:

  • Certain antibiotics
  • Diuretics
  • Prostaglandins

Drugs that can decrease urine sodium include the following:

  • Certain corticosteroids
  • Nonsteroidal anti-inflammatory drugs (NSAIDs)
Previous