Sodium

This test measures the amount of sodium that is in the blood or serum. Sodium is one of the main minerals called electrolytes that are found in the body.

Who is a candidate for the test?

If a doctor suspects one of the conditions that results from too high or too low a level of sodium, he or she may order this test.

How is the test performed?

In order to measure the amount of sodium in the blood, a blood sample is taken from a vein on the forearm or hand. First, the skin over the vein is cleaned with an antiseptic. Next, a rubber tube called a tourniquet is tied around the upper arm. This enlarges the veins in the lower arm by restricting blood flow through them. A fine needle is gently inserted into a vein, and the tourniquet is removed. Blood flows from the vein through the needle and is collected in a syringe or vial for testing in the laboratory. After the needle is withdrawn, the puncture site is covered for a short time to prevent bleeding.

Sodium is an electrolyte mineral, commonly known as salt. It helps maintain the balance of fluids and acids in the body.

Information

Sodium in the diet is measured in milligrams (mg). There is no recommended dietary allowance, called RDA, for sodium. But the National Academy of Sciences states that a person should consume at least 500 mg per day, and that healthy adults should stay within the range of 1,100 to 3,300 mg a day.

The American Heart Association recommends that for every 1,000 calories consumed, the sodium intake should be 1,000 mg and should not exceed 3,000 mg per day. The average sodium intake in the US is between 4,000 and 5,000 mg per day. One teaspoon of table salt contains 2,300 mg of sodium.

Sodium helps cause high blood pressure in some people. Anyone with this problem needs to reduce the amount of sodium in his or her diet.

What food source is the nutrient found in?

Sodium occurs naturally in most foods. It is even present in drinking water. Prepared foods contain the most sodium in the form of salt and food additives.

Convenience foods are designed to be quick and easy to transport, store prepare and eat. To do all this, they need stabilizers, preservatives, and ingredients to improve taste. Sodium does all of that. High amounts of sodium chloride are found in processed meats such as bacon, sausage, and ham, in canned soups and vegetables, and in many frozen foods. Most restaurant food is also high in sodium.

Food additives that contain sodium include:

How does the nutrient affect the body?

Sodium performs the following key functions in the body:

What is involved in preparation for the test?

Normally, no preparation is required for this test.

What do the test results mean?

The normal value for sodium in the blood is 136 to 146 mEq/liter. Sodium must stay in this range for all the cells in the body to function properly.

Sodium can become too high because of conditions including:

Many things can cause the sodium to become too low including:

Author:Kimberly Tessmer, RD, LD
Date Written:
Editor:Crist, Gayle P., MS, BA
Edit Date:09/30/02
Reviewer:Kathleen A. MacNaughton, RN, BSN
Date Reviewed:09/29/02

Author:Melinda Ratini, DO, MS
Date Written:
Editor:Crist, Gayle P., MS, BA
Edit Date:06/20/02
Reviewer:Kathleen A. MacNaughton, RN, BSN
Date Reviewed:06/18/02