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Sodium

Serum Sodium Na+
Serum (SST) mmol/L

About this test

Principal extracellular cation. Critical for osmolality, fluid balance, and neurological function. Disturbances must be corrected cautiously.

Reference Ranges

Sex Age Range Notes
All ≥ 18 yrs 135 – 145 Adult

Clinical Interpretation

Low / Decreased
Hyponatraemia — SIADH, heart failure, cirrhosis, Addison's disease, hypothyroidism, diuretics, vomiting, excess water intake.
High / Increased
Hypernatraemia — dehydration, diabetes insipidus, excessive sodium intake.

Related Tests

Urea Potassium
Specimen
Serum (SST)
Reporting Unit
mmol/L
Category
🧪 Clinical Biochemistry

⚠ Clinical Note
Reference ranges are indicative. Always interpret results in the context of the individual patient and local laboratory reference intervals, which may vary.