Serum Sodium

Function

Sodium is the primary extracellular electrolyte and is vital for maintaining fluid balance, blood pressure, and the proper functioning of nerves and muscles. It works in tandem with potassium and chloride to regulate the body's electrical signals.

Why it is Ordered

This test is a staple of the Basic Metabolic Panel (BMP) and is used to:

• Investigate symptoms of confusion, lethargy, or weakness.
• Monitor patients taking diuretics or blood pressure medications.
• Evaluate kidney function and adrenal health.
• Assess hydration status in cases of severe vomiting or diarrhea.

Associated Conditions

• Hyponatremia (Low): Can be caused by SIADH (Syndrome of Inappropriate Antidiuretic Hormone), heart failure, liver cirrhosis, or excessive water intake.
• Hypernatremia (High): Usually caused by dehydration, diabetes insipidus, or excessive salt intake.
• Kidney Disease: The kidneys are the primary regulators of sodium excretion; dysfunction leads to imbalances.

Clinical Importance

Sodium levels are critical because rapid changes can cause brain cells to swell (hyponatremia) or shrink (hypernatremia), leading to permanent neurological damage or death. Correction of sodium imbalances must be done slowly and carefully by medical professionals.