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Sodium is an electrolyte in your blood. It helps control the amount of fluid in your body. A level that is too high or too low can point to a problem with the kidneys, dehydration or another condition.[1]
On this page you can read what sodium is, what the guidelines say about a level that is too low or too high, what affects your level and which values are best read alongside it.
Also known as: Na, Na test, sodium. At the lab: NA.
Sodium is an electrolyte. Electrolytes are minerals that carry an electrical charge when they dissolve in water or body fluids. You find them in your blood, your urine, your tissues and other body fluids.[1]
Electrolytes help control the amount of fluid and the balance between acids and bases in your body. Sodium also helps your nerves and muscles work properly.[1]
You take in most of your sodium through your food. If you take in too much, your kidneys get rid of the extra sodium through your urine.[1]
A sodium test is a routine test that can tell you something about your general health. It helps find and monitor conditions that affect your balance of fluids, electrolytes and acidity.[1]
If your level is too high, you may feel thirsty, pass little urine, vomit, have diarrhoea, feel confused, or get muscle twitches or seizures. If your level is too low, you may feel weak and tired, feel confused, or get muscle twitches or seizures.[1]
An extremely high or extremely low level can lead to a coma without treatment and become life-threatening.[1]
Sodium is often measured together with other electrolytes. Your doctor usually looks at your sodium together with the results of other tests.[1]
Labplusarts, the lab BioProfile works with, uses a reference value of 135 to 145 mmol/l for sodium (NA). The lab calls a level between these limits normal.[2]
| Value | What it can mean | Who it is for |
|---|---|---|
| 135 to 145 mmol/l[2] | The lab calls this value normal | Anyone who has the sodium test (NA) done at this lab |
Source: the Labplusarts reference value for the sodium test (NA).[2]
A level that is too low can point to sodium loss through diarrhoea or vomiting. It can also point to a condition in which your body holds on to extra fluid, so the sodium becomes diluted, such as a condition of the kidneys, the liver or the heart, or certain conditions of the brain and the lungs. Other possible causes are certain medicines, a condition of the adrenal glands and malnutrition.[1]
A level that is too high can point to dehydration, for example from not drinking enough, diarrhoea or water tablets. It can also point to a condition of the adrenal glands, a condition of the kidneys or a rare condition affecting the body's water balance.[1]
BioProfile is working on its own zones for each value, from risk to optimal. A doctor reviews those zones before they appear in your result.
You get most of your sodium from your food. Not drinking enough can lead to dehydration, and that can raise your level. Sometimes your doctor asks you not to eat or drink for a number of hours before the test.[1]
Water pills can raise your sodium. Many over-the-counter painkillers and some antidepressants can lower it. Tell your doctor what you take, but never stop a medicine on your own without talking to them first.[1]
Diarrhoea and vomiting can make your sodium fall because you lose sodium. Diarrhoea can also make your level rise through dehydration.[1]
Your age, your sex and certain conditions can raise or lower your sodium.[1]
Sodium is included in BioProfile 77, 87, 121 and 150.[3]
The BioProfile editorial team wrote this page on 10 October 2026 from the sources below, which we read on 10 October 2026. Every number on this page appears in one of those sources, with that source's number next to it. An expert has yet to check this page; after that check, the expert's name and the date of the check will appear at the top. This page offers explanation, not a diagnosis. Discuss a value outside the range with your GP.
