Sodium Level

A sodium level measures the amount of sodium in your blood. Sodium is a key electrolyte that helps control fluid balance, supports normal nerve signaling, and enables muscles to contract. The test is usually performed on a blood sample taken from a vein and is commonly included in an electrolyte panel or a basic metabolic panel.

Your sodium level reflects the balance between sodium and water in your body. The kidneys, along with hormones such as aldosterone and antidiuretic hormone, constantly adjust this balance. Illnesses, medications, and fluid intake can all influence the result.

Checking your sodium level helps your care team evaluate symptoms like fatigue, confusion, headache, muscle cramps, or changes in alertness. It is used to assess dehydration or fluid overload and to monitor conditions that affect the kidneys, heart, liver, lungs, or endocrine system.

Clinicians also use this test to track the effects of medications, especially water pills and drugs that change water handling, and to guide fluid therapy in the hospital. Understanding your sodium level can help prevent complications that affect the brain, heart rhythm, and overall recovery from illness.

If your sodium level is lower than expected for your situation, your clinician may consider conditions that increase body water relative to sodium, such as certain medications, hormone changes, kidney or heart problems, or excessive fluid intake. If your level is higher than expected, causes like dehydration, reduced thirst or access to water, or kidney water losses may be explored.

Interpretation looks at your symptoms, exam findings, and related tests such as potassium, kidney function, glucose, and blood osmolality. Sometimes a repeat measurement or a different testing method is used to rule out lab artifacts. Do not change your fluid intake or medicines on your own; instead, discuss next steps with your clinician. Seek urgent care if you develop severe confusion, seizures, or worsening weakness.