24-Hour Sodium Urine Collection (Total Sodium Content)

Why This Test Is Done

Your doctor may order this test if they suspect conditions like kidney disease, excessive sweating, or certain hormonal imbalances that affect sodium levels. It can also help diagnose or monitor conditions like hypertension (high blood pressure) or syndrome of inappropriate antidiuretic hormone secretion (SIADH).

What to Expect Before the Test

You’ll need to collect all urine for a full 24-hour period, typically starting after midnight one day and ending just before midnight the next. Drink plenty of water unless instructed otherwise, but avoid adding extra salt to your diet during this time. Follow your doctor’s specific instructions carefully to ensure accurate results.

How the Test Is Performed

You’ll use a clean container to collect all urine produced during the 24-hour period. Empty your bladder at the start of the collection period, then discard that urine. Store all urine samples in a refrigerator until you return them to the lab. The lab will analyze the combined urine sample to measure total sodium content.

What the Results Mean

Results are typically reported as the total sodium amount excreted in urine per day. High sodium levels may indicate conditions like kidney problems or excessive salt intake, while very low levels could suggest conditions like kidney disease or inappropriate fluid retention. Your doctor will interpret the results in the context of your overall health and medical history.