Sodium Test – Why am I having this test?

The sodium test is done to determine how much sodium (Na) you have in your body. Sodium is an important mineral (electrolyte) that helps balance the amount of fluid you have in your body. If your sodium level is too high (hypernatremia), you can retain too much fluid. If your sodium level is too low (hyponatremia), you may lose too much fluid. Sodium is also important for proper nerve and muscle function.

You get sodium from the salt in your diet. Chemical messengers (hormones) made in glands located above your kidneys (adrenal glands) control how much sodium your body keeps or gets rid of in your urine.

You may have this test along with tests for other electrolytes as part of routine blood work. You may also have a sodium test if:

• You have signs of hypernatremia. These include:
  • Being thirsty.
  • Urinating less than normal.
  • Having muscle twitching.
• You have signs of hyponatremia, such as weakness or confusion.
• You are given fluids through an IV.
• You take water pills (diuretics).
• Your health care provider needs to monitor a condition that can cause your fluids to be unbalanced, such as:
  • High blood pressure.
  • Heart disease.
  • Kidney disease.
  • Liver disease.

What is being tested?

This test measures the amount of sodium in your blood.

What kind of sample is taken?

A blood sample is required for this test. It is usually collected by inserting a needle into a blood vessel.

Tell a health care provider about:

• All medicines you are taking, including vitamins, herbs, eye drops, creams, and over-the-counter medicines.

How are the results reported?

Your test results will be reported as a value that indicates the amount of sodium in your blood. Your health care provider will compare your results to normal ranges that were established after testing a large group of people (reference ranges). Reference ranges may vary among labs and hospitals. For this test, common reference ranges are:

• Adult/elderly: 136–145 mEq/L or 136/145 mmol/L (SI units).
• Child: 136–145 mEq/L.
• Infant: 134–150 mEq/L.
• Newborn: 134–144 mEq/L.

What do the results mean?

Results within the reference range are considered normal. Many different factors can cause a high or low sodium level.

• Common causes of hypernatremia include:
  • Making (secreting) too much or too little of certain hormones.
  • Not drinking enough fluids (dehydration).
  • Having too much salt in your diet.
• Common causes of hyponatremia include:
  • Secreting too much or too little of certain hormones.
  • Drinking too much water.
  • Losing sodium through sweating, vomiting, or diarrhea.
  • Taking a diuretic.
  • Having kidney disease.

Talk with your health care provider about what your results mean.

Questions to ask your health care provider

Ask your health care provider, or the department that is doing the test:

• When will my results be ready?
• How will I get my results?
• What are my treatment options?
• What other tests do I need?
• What are my next steps?

Summary

• The sodium test is done to determine how much sodium (Na) you have in your body. Sodium is an important mineral (electrolyte) that helps balance the amount of fluid you have in your body.
• You may have this test as part of routine blood work. You may also have the test to check for certain problems or to monitor various conditions.
• Abnormal sodium levels occur with many conditions, such as secreting too much or too little of certain hormones or drinking too much or too little water.
• Talk with your health care provider about what your test results mean.