Urine Sodium
Urine sodium measures how much of the mineral sodium your kidneys are releasing into the urine. It largely reflects the salt in your recent diet and how your body is balancing fluids.
Because sodium excretion shifts with diet and hydration, this test helps clinicians understand the cause of abnormal blood sodium, dehydration, or certain kidney and hormone conditions. It's most useful when interpreted alongside your blood tests and clinical situation.
Higher urine sodium can reflect a salty diet or the kidneys appropriately releasing sodium. In the setting of certain conditions, it can also help distinguish causes of low blood sodium or kidney stress. The number means little in isolation and needs clinical context.
Lower urine sodium often means the body is holding on to sodium, such as during dehydration or reduced blood flow to the kidneys. Like a high value, it's meaningful only alongside your overall picture.
There's no single normal value because urine sodium depends heavily on diet; a rough reference for a 24-hour collection is around 40 to 220 mmol/day. Your clinician interprets it together with your blood sodium and clinical context.
Sources
Educational context only, not medical advice or a diagnosis. Reference ranges vary by lab, age and sex; always discuss your results with a clinician.