Sodium

The sodium test measures the concentration of sodium in your blood. Sodium is a key electrolyte that helps regulate fluid balance, blood pressure, and how nerves and muscles function.

This test uses a blood sample taken from a vein and is commonly performed with other electrolytes and kidney function tests. Together, these results help your care team understand your overall fluid and electrolyte status.

Keeping sodium in a healthy range is essential for normal brain, nerve, and muscle activity. Levels can shift with dehydration, excess water intake, kidney or heart problems, liver disease, and hormone disorders that affect water and salt balance. Gastrointestinal losses such as vomiting or diarrhea can also affect sodium.

Clinicians order this test to evaluate symptoms like fatigue, confusion, headache, muscle cramps, or seizures, to monitor people receiving diuretics or intravenous fluids, and to guide hospital care. Knowing whether sodium is low or high helps tailor treatment, which may include adjusting fluids, reviewing medications, and treating any underlying condition.

Your provider will interpret your sodium result in the context of your age, symptoms, medications, and other labs. Small deviations may not need urgent action, while larger or rapid changes can be more serious and require closer monitoring.

If your result is outside the expected range, follow‑up may include repeating the test, measuring related values such as potassium, chloride, osmolality, glucose, and kidney function, and reviewing your fluid intake and losses. Treatment focuses on the cause and is adjusted carefully to avoid changing sodium too quickly.