EmpeiriaSodium
Also known as
Na, serum sodium
Na⁺ inorganic ion
unverified These explanations are written to be easy to read and have not yet been checked against a source. The ranges and measurement notes on this page show theirs.
definition unverified
A measure of the balance between salt and water in your blood. It says more about your water than about how much salt you eat.
A measure of the balance between salt and water in your blood. It says more about your water than about how much salt you eat.
No clinical version written yet.
if high unverified
This is nearly always dehydration. It shows up most in people who cannot easily get a drink on their own.
This is nearly always dehydration. It shows up most in people who cannot easily get a drink on their own.
No clinical version written yet.
if low unverified
Usually too much water relative to salt rather than too little salt. Causes confusion and headache when it falls quickly.
Usually too much water relative to salt rather than too little salt. Causes confusion and headache when it falls quickly.
No clinical version written yet.
caveats unverified
Cutting salt from your diet does not usually change this number. Your kidneys adjust water to hold it steady.
Cutting salt from your diet does not usually change this number. Your kidneys adjust water to hold it steady.
No clinical version written yet.
What this substance is
- formula
- Na⁺
- mass
- 22.99 g/mol
- monoisotopic
- 22.98922
- charge
- 1
- nucleus
- 11 protons, 12 neutrons (23Na)
- electrons
- 10: 1s² 2s² 2p⁶
- InChIKey
- FKNQFGJONOIPTF-UHFFFAOYSA-N
- ChEBI
- CHEBI:29101
Drawn from ChEBI's own curated 2D drawing, accepted only after its InChIKey, formula and charge matched the ChEBI release. Nothing here is hand-entered. Two masses are given because they answer different questions: the average is natural-abundance weighted and drives unit conversion; the monoisotopic value uses only the commonest isotope of each element and is what mass spectrometry measures.
3D model · Sodium
A schematic atom: a nucleus of 11 protons and 12 neutrons (the most common isotope, 23Na), inside its electron shells, 1s² 2s² 2p⁶. The configuration matches the NIST Atomic Spectra Database ground state of Na II (1S0). The cloud is drawn as nested spheres because that term is an S state: the electron density really is spherical. Not to scale: shells are spaced on a square-root scale so the inner ones stay visible, and the nucleus is magnified about ten-thousand-fold.
Reference ranges
Checking your own result against this range needs the running application; this is a static copy. Nothing you type anywhere in Empeiria is ever sent to a server.
This open edition shows a range only where a public-domain or openly licensed source states one, and none does for this marker yet. Compare your result with the range printed on your own lab report.
How it is measured
In practice
A health worker takes a small amount of blood from a vein in your arm with a needle. Sodium is usually checked as part of a larger blood panel. You may be asked to fast or to pause some medicines first. Do not stop any medicine unless your provider tells you to.
Venous blood sample, usually as part of an electrolyte or basic metabolic panel. The provider may temporarily stop drugs that affect the result, including antibiotics, antidepressants, some antihypertensives, lithium, NSAIDs and diuretics. Fasting for several hours may be requested.
Before the test
- Ask your provider whether you need to fast for several hours.
- Tell your provider about every medicine you take; do not stop any unless told to.
Where: laboratory
Sources: Sodium Blood Test, MedlinePlus (U.S. National Library of Medicine); Sodium blood test, MedlinePlus Medical Encyclopedia cited · not yet checked by a person
In the lab
Direct ion-selective electrode
A special membrane produces a tiny voltage that depends on how much sodium is present. The machine measures that voltage.
A sodium-selective membrane (on many analysers a neutral-carrier ionophore) in direct contact with the undiluted sample develops an electrical potential, measured against a reference electrode and converted to sodium concentration.
Sources: Discrepancies in Electrolyte Measurements by Direct and Indirect Ion Selective Electrodes due to Interferences by Proteins and Lipids. J Lab Physicians 2020 (PMC open access); Laboratory Procedure Manual, Sodium (Roche cobas ISE), NHANES August 2021 - August 2023, CDC/NCHS cited · not yet checked by a person
What it reports on
-
nephron tubule
regulated by
The kidney governs how much sodium leaves the body, and its tubules take needed minerals back into the blood.
-
adrenal gland
regulated by
Aldosterone from the adrenal glands tells the kidneys to keep more sodium in the blood.
Associated symptoms
- high Feeling thirsty all the time · suggestive · common
-
low
Trouble thinking clearly
· suggestive · common
Falling extracellular osmolality draws water into brain cells.
- low Headaches · non specific · occasional
- low Feeling sick to your stomach · non specific · occasional
- low Muscle cramps or spasms · non specific · occasional
Conditions this marker features in
-
high
High blood sodium
· defining
Defined as serum sodium above 145 mmol/L; above 160 mmol/L is severe. A falsely high sodium can occur when blood protein or fat is low, and should be ruled out first.
-
low
Low blood sodium
· defining
Hyponatraemia is defined by a serum sodium below 135 mmol/L. Some sources use below 136.