Sodium

An electrolyte the kidneys hold within a narrow range. It is read as part of kidney function rather than on its own, and it is accredited for venous blood only.

Sodium in the Biomarker Guide — what it is, why it is tested, and what moves the number.

Add-on markers can only be added to venous samples.

Timing

No fasting needed and no particular time of day. Drink normally. Dehydration and drinking a very large volume of water shortly beforehand both move sodium.

Turnaround: the lab reports this test within 24 hours of receiving your sample, counted in working days. Most samples reach them within about 3 days of posting. Full detail on our Turnaround Times page.

We do not interpret results. Not medical advice or a diagnosis.