Sodium concentration in 24-hour urine collection (mass concentration)

Why This Test Matters

Sodium is essential for maintaining proper fluid balance, nerve function, and blood pressure. Your kidneys normally filter out excess sodium through urine. A 24-hour urine sodium test helps doctors evaluate how well your kidneys are working to manage sodium levels, especially if you have conditions like high blood pressure, kidney disease, or heart problems.

When You Might Need This Test

Your doctor may order this test if you have symptoms like swelling (edema), high blood pressure, frequent urination, or if they suspect kidney, heart, or kidney-related disorders. It’s also used to monitor long-term sodium balance in people with chronic conditions.

How the Test Works

You’ll collect all your urine for a full 24-hour period in a special container. The sample is then sent to a lab to measure sodium levels. This method gives a more accurate picture than a single urine test, as it accounts for daily variations.

What to Expect Before the Test

No special preparation is needed, but you’ll need to keep a record of all urine output (including during sleep) in a timed container. Drink enough fluids to produce urine consistently but avoid excessive salt intake unless directed otherwise.