Urea Nitrogen, 24-Hour Urine without Creatinine

Quest Diagnostics

Sample type: Urine

Requires fasting: No

Sample collection required at Quest Diagnostics location

Details

Urea Nitrogen, 24-Hour Urine without Creatinine - This quantitative urea nitrogen test, performed with a 24-hour urine specimen, may help estimate nitrogen balance and determine protein need in patients in critical conditions or receiving intravenous administration of nutrition.

Biomarker summary

Urea Nitrogen, 24 Hr Urine

Additional details

Estimated days for results: Results should be available in 2 - 5 business days after the sample is collected

Details

Urea is the main nitrogen-containing product of protein breakdown and makes up over 75% of total nonprotein nitrogen excreted. Approximately 90% of the urea excretion is through the kidneys, and the rest is through the gastrointestinal tract and skin. Because urea secretion is closely related to protein catabolism, urinary urea, commonly expressed by the concentration of urinary urea nitrogen, may be used to assess nitrogen balance and guide protein intake [1,2]. Blood and urinary urea levels were previously used as kidney function markers, but are only considered useful in certain clinical scenarios; they have been generally replaced by creatine levels [1].

Urinary urea nitrogen level may be increased in individuals with hyperthyroidism or excess protein intake or breakdown [3]. It may be decreased in individuals with malnutrition, kidney damage or insufficiency, low-protein and high-carbohydrate diet, or liver disease. Pregnant persons and healthy children may also have low urinary nitrogen levels [3].

The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings.

References
1. Lamb EJ, et al. Kidney function tests. Rifai N, et al. eds. Tietz Textbook of Laboratory Medicine. 7th ed. Elservier Inc; 2022
2. Oh MS, et al. Evaluation of renal function, water, electrolytes, and acid-base balance. In: McPherson RA, et al, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Elsevier; 2021
3. Rao LV, et al. Laboratory tests. In: Rao LV, eds. Wallach's Interpretation of Diagnostic Tests. Pathways to Arriving at a Clinical Diagnosis. 11th ed. Wolters Kluwer; 2020.

What type of sample is required for this test?

10 mL urine aliquot from a well-mixed 24-hour collection - no preservative

Test Resources

For more information, please consult your healthcare provider.

Average sample processing time

2–5 business days

Reference range

6-17 g/24 h

Health categories

Patient instructions

Collection Options with Fullscript
Sample collection requires a test kit that can be picked up at a nearby Quest Diagnostics Patient Service Center.

Quest Diagnostics Patient Service Centers (PSC)

Location: Visit a nearby Quest Diagnostics Patient Service Center.
Cost: $10 sample collection fee (paid during lab order checkout).
Scheduling: Schedule your appointment here. Appointments are recommended to reduce wait times. Walk-ins are accepted, but may experience delays. Aim to arrive 10 minutes before your appointment.
Collection Instructions:

Bring a valid ID.
Bring your digital or printed requisition form, available in the Labs tab of your Fullscript account.

Check-in: Scan the QR code from your confirmation email or follow kiosk instructions.
More Info: Quest Diagnostics collection guide

In-office phlebotomy instructions

Specimen

Preferred Specimen(s): 10 mL urine aliquot from a well-mixed 24-hour collection - no preservative
Alternative: NA
Minimum Volume: 2 mL
Collection Instructions: NA

Storage and shipping instructions