Sodium Blood Test Test
A sodium blood test measures the amount of sodium in your blood. Sodium helps control fluid balance and helps your nerves and muscles work properly. High or low levels can signal health issues like dehydration, kidney problems, or other conditions.
What this test measures
This test measures the amount of sodium in your blood. Sodium is an electrolyte that helps control fluid balance, acid-base balance, and nerve and muscle function.
What your results mean
Reference ranges vary by laboratory and by your age and sex. MedlinePlus does not publish a single normal range for this test — always read your result against the range printed on your own lab report and discuss it with your provider.
Higher-than-normal results
Higher than normal sodium levels may be a sign of dehydration (from not drinking enough, diarrhea, or diuretics), a disorder of the adrenal glands, kidney disease, or diabetes insipidus.
Lower-than-normal results
Lower than normal sodium levels may be a sign of sodium loss from diarrhea or vomiting, conditions that cause fluid retention (kidney disease, cirrhosis, heart failure), certain brain/lung diseases, some cancers, certain medicines, Addison disease, or malnutrition.
Frequently asked questions
What is a sodium blood test?
It measures the amount of sodium in your blood. Sodium is an electrolyte that helps control fluid balance and nerve/muscle function.
Why is this test done?
It is often part of a routine checkup or an electrolyte panel to help find or monitor conditions that affect fluid, electrolyte, or acid-base balance.
What can cause high sodium levels?
High levels may be due to dehydration, adrenal gland disorders, kidney disease, or diabetes insipidus.
What can cause low sodium levels?
Low levels may result from diarrhea, vomiting, fluid-retaining conditions (like heart failure or cirrhosis), certain medicines, Addison disease, or malnutrition.
Do abnormal results always mean a medical condition?
No. Certain medicines, age, sex, and other factors can affect sodium levels. Your provider will interpret results along with other tests.
Related lab tests
Sources
- MedlinePlus: Sodium Blood Test — NIH MedlinePlus
Last updated . Information is aggregated from official public sources and is not a substitute for professional medical care.