SODIUM

SODIUM - serum

Application: Assessment of fluid and electrolyte status, especially in patients with renal or cardiac disease, possible sodium losing states, and in those receiving intravenous fluids.


Explanation: Sodium is the major cation in the extracellular space, and its concentration is dependent on state of hydration, body sodium content and water shifts between plasma and other body fluid compartments.  Intravenous therapy with normal saline may cause hypernatremia, as will aldosterone excess.
   Volume replacement with dextrose may cause hyponatremia-- as will renal or cardiac disease, due to fluid retention (dilutional hyponatremia). Other causes of sodium loss are aldosterone deficiency, gastrointestinal or renal sodium loss, or excessive sweating.     Hyponatremia also occurs in a small percentage of patients on diuretic therapy, especially the elderly.


Specimen: 5 ml blood in red- or green-top tube.


Reference Interval:
135-145 mEq/L. (Adult/Child)
134-150 mEq/L   (Infant)
134-144 mEq/L   (newborn)