Serum sodium

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Blood test

Sodium - serum; Na+

The normal range of sodium is 135 to 145 mEq/L (milliequivalents per liter).

Higher-than-normal sodium levels may indicate many different conditions. To help determine the cause, your health care provider will consider the total amount of fluid in your body. This is done during a physical exam by looking at the turgor of your skin and swelling in the ankles, feet, and legs.

• If the amount of fluid in your body (total body water) is low, you may have lost water due to excessive sweating, diarrhea, use of diuretics (for example, furosemide, bumetanide, or torsemide), or burns.
• If your total body water is normal, high sodium levels may indicate diabetes insipidus or too little of the hormone vasopressin.
• If your total body water is high, this may indicate hyperaldosteronism (too much of the hormone aldosterone), Cushing's syndrome (too much of the hormone cortisol), or too much salt or sodium bicarbonate ingestion.

Lower-than-normal sodium levels also may be classified according to total body water:

• Low total body water may indicate dehydration, vomiting, diarrhea, over diuresis, or ketonuria (excretion or loss of ketone bodies in urine).
• Near-normal total body water may indicate SIADH, too much of the hormone vasopressin, underactive thyroid ( hypothyroidism), or Addison's disease (low production of cortisol and other hormones).
• An increase in total body water may indicate congestive heart failure, nephrotic syndrome or other kidney disease, or cirrhosis of the liver.

Additional conditions for which the test may be performed include:

• Acute adrenal crisis
• Diabetic hyperglycemic hyperosmolar coma
• Drug-induced hypothyroidism
• Hepatorenal syndrome
• Hypopituitarism

Review Date: 10/25/2006
Reviewed By: Robert Hurd, M.D., Department of Biology, College of Arts and Sciences, Xavier University, Cincinnati, OH. Review provided by VeriMed Healthcare Network.