Sodium, 24-hr Urine
CPT Code(s):
84300
Turnaround Time:
8 hours
Specimen Requirements
Preferred Specimen:
Urine
Minimum Volume:
5.0 mL
Transport Container:
Yellow Top Urine Tube or Plastic Urine Cup
Transport Temperature:
Room Temperature
Collection Instructions:
Collect random urine without preservatives.
Rejection Criteria:
Unlabeled specimen or name discrepancy between specimen and request label; specimen in expired transport container; specimen received after prolonged delay; specimen in nonsterile or leaking container.
Stability Criteria
Room Temperature:
7 days
Refrigerated:
7 days
Frozen:
7 days
Clinical Significance
Measuring sodium levels in a 24-hour urine collection can provide valuable clinical insights into various aspects of kidney function, electrolyte balance, and overall health. Here are some of the clinical significances of sodium in a 24-hour urine sample:
1. **Evaluation of Electrolyte Balance**: Sodium is a key electrolyte in the body, and its levels in urine reflect the balance between intake, excretion, and reabsorption. Abnormal sodium levels in a 24-hour urine collection may indicate disturbances in electrolyte balance, such as dehydration, overhydration, or certain kidney disorders.
2. **Assessment of Kidney Function**: The kidneys play a crucial role in maintaining sodium homeostasis by regulating its reabsorption and excretion. Abnormal sodium levels in a 24-hour urine sample can provide valuable information about kidney function and may indicate impaired renal tubular function, renal tubular disorders, or certain kidney diseases, such as acute kidney injury or chronic kidney disease.
3. **Evaluation of Hydration Status**: Sodium levels in urine can provide insights into an individual's hydration status. Low urine sodium levels may indicate dehydration, while high urine sodium levels may suggest overhydration or excessive salt intake.
4. **Monitoring Sodium Intake**: Measuring sodium levels in a 24-hour urine collection can help assess sodium intake, especially in individuals with conditions such as hypertension or heart failure, where sodium restriction is important for management.
5. **Assessment of Salt Sensitivity**: Sodium sensitivity refers to the degree to which blood pressure changes in response to changes in sodium intake. Measuring sodium levels in a 24-hour urine sample can help identify individuals who are salt-sensitive, which may influence treatment decisions for conditions like hypertension.
6. **Evaluation of Renal Tubular Disorders**: Conditions such as renal tubular acidosis (RTA) and Bartter syndrome are characterized by abnormalities in renal tubular function, including impaired sodium reabsorption. Measurement of sodium levels in a 24-hour urine collection can aid in the diagnosis and monitoring of these disorders.
7. **Assessment of Fluid and Volume Status**: Urine sodium levels can also provide insights into an individual's fluid and volume status. Low urine sodium levels may be seen in conditions associated with reduced effective circulating volume, such as congestive heart failure or cirrhosis, while high urine sodium levels may be observed in conditions associated with increased extracellular fluid volume, such as primary aldosteronism.
Overall, measuring sodium levels in a 24-hour urine collection is an important component of the comprehensive evaluation of kidney function, electrolyte balance, hydration status, and volume status in clinical practice. Interpretation of urine sodium levels should be done in conjunction with other clinical parameters and in the context of the patient's overall health status.