The 24-Hour Urinary Sodium test measures the total amount of sodium (salt) excreted in the urine over a full 24-hour period. It is a key tool for evaluating the body's sodium balance, which is closely regulated by the kidneys and is vital for fluid balance, nerve function, and blood pressure control.
Purpose and Significance Assessment of Sodium Intake: It is the most reliable way to estimate a person's average dietary salt intake, as sodium excretion generally equals intake over time in a stable state.
Kidney Function: Helps determine if the kidneys are appropriately retaining or excreting sodium, particularly in relation to blood sodium levels.
Differential Diagnosis: Used to help differentiate between causes of abnormal serum sodium levels (hyponatremia or hypernatremia) and acute kidney injury, distinguishing between kidney-related (renal) causes and fluid loss (pre-renal) causes.
Monitoring Conditions: Useful for monitoring patients with conditions like hypertension (high blood pressure), congestive heart failure (CHF), cirrhosis, and adrenal gland disorders (e.g., hyperaldosteronism), which affect fluid and electrolyte balance.