Sodium
Sodium is the main electrolyte outside cells; together with water it regulates the amount of body fluid, blood pressure and nerve function. The body maintains it precisely through thirst and the kidneys (the hormone ADH).
| Rating | Range | What it means |
|---|---|---|
| Talk to a doctor | below 135 mmol/L | Low sodium — seek advice. |
| Good | 135 – 145 mmol/L | Within the reference range. |
| Talk to a doctor | 145 mmol/L and above | High sodium — seek advice. |
Why it matters
An abnormal value points to hydration, the kidneys, or hormones.
If it’s low
Low sodium (hyponatremia) is often an excess of water relative to salt. It can cause headache, nausea, confusion; a rapid fall is dangerous for the brain.
If it’s high
High sodium (hypernatremia) almost always means too little water relative to salt — dehydration (drinking too little, losses). It shows up as thirst, confusion.
What to do
Sodium mainly reflects water — you do not fix it by adding/removing salt on your own. An abnormality (especially with confusion) belongs to a doctor; mild fluctuations often follow hydration.
Read together with
Potassium · Chloride · eGFR
Part of the guide: Kidneys & electrolytes →
Articles about this marker
- Blood chemistry tests: normal values for ALT, AST, GGT, CRP, CK, creatinine and glucoseReading your report
- Potassium high or low? What your potassium and sodium results meanMarker explained
This content is for information only and is not a substitute for medical advice. Talk to your doctor about your results.
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