Serum Sodium

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What do Abnormal Results Mean?

Greater-than-normal sodium levels may indicate many different conditions. It is helpful to your physician to also consider the amount of fluid in your body that is outside cells (extracellular volume):

• If the extracellular volume is low, you may have lost water due to burns, excessive sweating, diarrhea, or osmotic/loop diuretics (usually not thiazides).
• If the extracellular volume is normal, this may indicate diabetes insipidus
• If the extracellular volume is high, this may indicate hyperaldosteronism, Cushing's Syndrome, or salt or sodium bicarbonate ingestion

Lower-than-normal sodium levels (hyponatremia) may be similarly classified according to total body water:

• A decrease in total body water (hypovolemic hyponatremia) indicates dehydration, over diuresis, ketonuria (excretion of ketone bodies in urine), vomiting, or diarrhea
• Near-normal total body water (normovolemic hyponatremia) indicates syndrome of inappropriate antidiuretic hormone secretion (SIADH), hypothyroidism, or Addison's Disease
• An increase in total body water (hypervolemic hyponatremia) indicates kidney failure, congestive heart failure, nephrotic syndrome, or cirrhosis of the liver

• acute adrenal crisis
• diabetic hyperglycemic hyperosmolar coma
• drug-induced hypothyroidism
• hepatorenal syndrome
• hypopituitarism
• hypothyroidism
• hypothyroidism - primary
• hypothyroidism - secondary