Urea nitrogen urine test

Definition

Urine urea nitrogen is a test that measures the amount of urea in the urine. Urea is a waste product resulting from the breakdown of protein in the body.

Alternative Names

Urine urea nitrogen

How the Test is Performed

A 24-hour urine sample is often needed. You will need to collect your urine over 24 hours. Your health care provider will tell you how to do this. Follow instructions exactly to ensure accurate results.

How to Prepare for the Test

No special preparation is needed.

How the Test will Feel

The test involves only normal urination. There is no discomfort.

Why the Test is Performed

This test is mainly used to check a person's protein balance and the amount of food protein needed by severely ill people. It is also used to determine how much protein a person takes in.

Urea is excreted by the kidneys. The test measures the amount of urea the kidneys excrete. The result can show how well the kidneys are working.

Normal Results

Normal values range from 12 to 20 grams per 24 hours (428.4 to 714 mmol/day).

Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your provider about the meaning of your specific test results.

What Abnormal Results Mean

Low levels usually indicate:

• Kidney problems
• Malnutrition (inadequate protein in diet)

High levels usually indicate:

• Increased protein breakdown in the body
• Too much protein intake

Risks

There are no risks with this test.

References

Agarwal R. Approach to the patient with renal disease. In: Benjamin IJ, Griggs RC, Wing EJ, Fitz JG, eds. Andreoli and Carpenter's Cecil Essentials of Medicine. 9th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 26.

Riley RS, McPherson RA. Basic examination of urine. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 29.