What does blood test for potassium and sodium identify?

Potassium and Sodium Test (Blood)

Measures the levels of potassium and sodium in the blood. These minerals are electrolytes, which are substances that conduct electrical current. Electrolytes, including potassium and sodium, are needed to regulate the body's fluid balance, the acidity or alkalinity of the body fluids (pH balance), and muscle function.

Why the test is done

To evaluate:

- Changes in fluid and electrolyte balance, such as those that can occur with chronic kidney disease, diarrhea, or vomiting

- Addison disease

- Cushing syndrome

- Acid-base disorders, such as diabetic ketoacidosis

- Primary hyperaldosteronism

- Salt-losing nephropathy

This test may also be used to monitor patients who are taking medications, such as diuretics, that affect potassium levels or who are at risk for potassium or sodium imbalances.