Sodium Urine Test

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Latest Edit: Hector 2014-03-21 (EDT)

See Also Lab Tests

Sodium is the major cation in the extracellular space. The sodium urine test can be used to assess fluid and electrolyte abnormalities. It can also be used to monitor therapy for these abnormalities.[1]


  • This test evaluates sodium balance in the body by determining the amount of sodium excreted in urine over 24 hours.
  • This is an important test to administer, particularly when serum sodium concentration is low.
  • Factors that regulate sodium balance include functions of: aldosterone, natriuretic hormone, and Antidiuretic Hormone (ADH).

Patient Preparation

  • No fasting is required
  • Factors which can cause increased levels:
  • dietary salt intake
  • Drugs: antibiotics, cough, medicines, caffeine, laxatives, and diuretics (e.g. spironolactone)
  • Factors which can cause decreased levels:
  • Drugs: steroids

Clinical Implications


High levels indicate:

  • Dehydration
  • Adrenocortical insufficiency
  • Diuretic therapy
  • Syndrome of inappropriate antidiuretic hormone secretion (SIADH)
  • Diabetic ketoacidosis
  • Chronic renal failure

Low levels indicate:

Associated Tests


  1. Pagana Kathleen D, Pagana Timothy J (2006) Mosby's Manual of Diagnostic and Laboratory Tests, Mosby.