Lab test glossary · Other
Sodium: what it means
Also known as: Na
Sodium is an electrolyte that regulates fluid balance; abnormal levels usually reflect hydration or kidney/hormone issues.
What it measures
Sodium is the main electrolyte governing your body's water balance. Because of that, an abnormal sodium is often really a water problem — too much or too little relative to sodium — which is why it's interpreted with hydration and kidney function in mind.
Typical range
Often roughly 135–145 mmol/L.
Reference ranges differ between labs and are printed on your own report — always read your result against that range, not a general one.
What a high result can mean
- Dehydration or insufficient water intake
- Some hormonal conditions
A high value is a starting point for a conversation, not a diagnosis — many causes are benign or temporary.
What a low result can mean
- Overhydration or fluid retention
- Certain medications (e.g. some diuretics)
- Hormonal and kidney conditions
Why the trend matters
Sodium shifts with fluid status, so the trend and the clinical context matter more than an isolated value.
When to talk to your doctor
A sodium clearly outside the range is worth discussing with your doctor, especially with confusion, weakness, or marked thirst.
This page is general education about a common lab test — it isn’t medical advice and can’t interpret your specific result. What a value means depends on your history, symptoms, and the rest of your labs, which is a conversation for you and your clinician.