What it measures
Sodium is the main salt in the blood and helps control how much water the body holds. The level reflects the balance between salt and water more than how much salt someone eats.
Why people test it
- Part of a kidney or electrolyte panel, often called U&Es.
- Monitored on medicines that can lower it, such as some diuretics and antidepressants.
- Checked with dehydration, sickness and diarrhoea, or confusion.
Typical range
Ranges vary between labs, with the method used, age and sex, and your report shows the lab's own range. One NHS lab gives 133 to 146 mmol/L. Source: North Bristol NHS Trust, Severn Pathology: sodium.
Finger-prick or vein?
A finger-prick sample is usually fine for sodium, which often comes in a home kidney panel. A vein draw works too and is used when it is part of a larger panel.