Sodium Blood Test

This test measures the concentration of sodium in your serum, by ion-selective electrode at Quest. Sodium is the main positively charged electrolyte outside your cells; together with chloride and bicarbonate it shapes fluid balance and acid-base balance. Clinicians often read sodium alongside the other electrolytes, glucose and kidney markers.

People re-checking a sodium that was low or high on a previous panel; people taking medicines that can affect sodium, such as diuretics (water pills) or certain antidepressants, whose clinician wants a check; people with heart, kidney, liver or adrenal conditions; and anyone with symptoms that can come from abnormal sodium, such as confusion, weakness, fatigue or muscle twitching.

Any time of day; no fasting is needed. If you are monitoring sodium on a medicine, testing under similar conditions each time (similar fluid intake and no recent bout of vomiting or diarrhea) makes results easier to compare.

Quest's reference range for this code is 135-146 mmol/L. A low sodium (hyponatremia) can come from sodium loss through vomiting or diarrhea, or from the body holding extra water, as in heart failure, kidney disease or cirrhosis; it can also be caused by certain medicines (including some over-the-counter pain relievers and some antidepressants), Addison disease or some lung, brain and other conditions. A high sodium (hypernatremia) most often reflects dehydration, from not drinking enough, diarrhea or diuretics, and less often adrenal or kidney conditions or diabetes insipidus. Very high or very low sodium can be serious and needs prompt medical attention. Mild abnormalities do not always mean a condition needing treatment; clinicians read sodium with your other electrolytes and history. JustLabs results are informational; review them with a clinician.