What Is a 24-Hour Urine Test?

  • Medical Author:
    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

  • Medical Editor: Dennis Lee, MD
    Dennis Lee, MD

    Dennis Lee, MD

    Dr. Lee was born in Shanghai, China, and received his college and medical training in the United States. He is fluent in English and three Chinese dialects. He graduated with chemistry departmental honors from Harvey Mudd College. He was appointed president of AOA society at UCLA School of Medicine. He underwent internal medicine residency and gastroenterology fellowship training at Cedars Sinai Medical Center.

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Ask the experts

My doctor just ordered a 24-hour urine test. Why is it necessary to collect my urine for 24 hours, when I normally just provide a single urine sample at the doctor's office?

Doctor's response

A single sample of urine is normally used to determine whether there are increased amounts of specific substances in your urine, such as glucose, red blood cells, white blood cells, or protein. The urinalysis is a "snapshot" assessment of your urine at one point in time. The urinalysis is a valuable screening tool for urinary tract infections, kidneys diseases, and other conditions.

However, sometimes doctors need to know how much urine your body is producing in a day or how much of a particular substance (for example, protein, aldosterone, sodium, potassium, or urea nitrogen) is eliminated in a day. A single-specimen urinalysis cannot provide this information, so patients are instructed to collect all their urine produced in a 24-hour period. A special container is provided for this purpose, which is returned to the laboratory after you have finished the urine collection at home.

For example, a doctor will order a 24-hour urine collection for creatinine in order to calculate how well a patient's kidneys are functioning. A doctor may also order a 24-hour urine collection for a hormone (5-HIAA) in order to exclude carcinoid syndrome. Today, I (Dr. Lee) ordered a 24-hour urine collection to measure a patient's rate or urine excretion of copper to exclude Wilson's disease (a genetic disorder that can cause excessive copper accumulation in the body and cause hepatitis and brain damage).

Medically reviewed by John A. Daller, MD; American Board of Surgery with subspecialty certification in surgical critical care

REFERENCE:

"24-Hour Urine Protein"
U.S. National Library of Medicine


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Reviewed on 6/22/2017

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