Sodium (na) blood test

A sodium test checks for how much sodium is in the blood. Sodium helps the body keep the right mix of water and minerals.

A sodium blood test is done to:

• Check on the mix of water and certain minerals in the body.
• Find the cause of symptoms from low or high levels of sodium.
• Check on the progress of diseases of the kidneys or adrenal glands.

A health professional uses a needle to take a blood sample, usually from the arm.

In general, you don't need to do anything to prepare for your child's test. Your doctor may give you some specific instructions.

Each lab has a different range for what's normal. Your lab report should show the range that your lab uses for each test. The normal range is just a guide. Your doctor will also look at your results based on your age, health, and other factors. A value that isn't in the normal range may still be normal for you.

Results are ready in 1 day.

Many conditions can affect sodium levels. Your doctor will talk with you about any abnormal results that may be related to your symptoms and past health.

High values

• High sodium levels (hypernatremia) can be caused by a high-sodium diet or by not drinking enough water and being dehydrated. Dehydration may also be caused by medicines (such as diuretics), severe vomiting or diarrhea, Cushing's syndrome, kidney disease or injury, diabetic ketoacidosis, or a condition called diabetes insipidus that makes it hard to balance the water level in the body.
• High sodium levels can also be caused by high levels of the hormone aldosterone (hyperaldosteronism).

Low values

• Low sodium levels (hyponatremia) can be caused by a lot of sweating, burns, severe vomiting or diarrhea, drinking too much water (psychogenic polydipsia), or poor nutrition.
• Low sodium levels can also be caused by underactive adrenal glands or thyroid gland, heart failure, kidney disease, cirrhosis, cystic fibrosis, or SIADH (syndrome of inappropriate antidiuretic hormone secretion).