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Urine Uric Acid, 24-Hour

How much uric acid your kidneys pass in urine over a full day. It is used mostly to look into kidney stones and gout.

AI-verified against cited sources. Awaiting expert reviewLOINC 3087-4

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What it is

Uric acid is a waste product made when your body breaks down purines, which come from your own cells and from some foods. Most of it dissolves in blood and leaves in your urine. This test adds up all the uric acid in every urine sample you collect over 24 hours and reports it in milligrams per day.

Why it matters

Doctors use this test when someone has kidney stones or gout, or to find out why uric acid is high in the blood. Too much uric acid in urine, especially when the urine is acidic and the amount of urine is low, can make uric acid stones more likely and can also help calcium stones form. It also helps show whether a high blood level comes from making too much or from removing too little.

If it’s low

Less uric acid than usual passed into your urine. This is often because some urine was missed during the collection. It can also mean the kidneys are not removing uric acid as well as usual, which is one reason blood uric acid can rise. Your clinician can work out which.

Common causes

  • Missed urine, or a collection shorter than 24 hours
  • Medicines that lower uric acid
  • Chronic kidney disease that reduces how much uric acid the kidneys can remove
  • Other long-term kidney conditions, such as chronic glomerulonephritis
  • Long-term alcohol use
  • Lead poisoning (rare)

What can help

  • Ask whether the collection was complete, since labs often check urine creatinine
  • Ask whether a repeat collection would be worthwhile

If it’s high

More uric acid than usual passed into your urine over the day. A diet rich in purines is a common reason. This result does not say what is wrong by itself, so your clinician reads it with your urine pH and volume, your blood uric acid and your history.

Common causes

  • A diet high in purine-rich foods
  • Gout
  • Some gout medicines that help the kidneys remove uric acid
  • Fanconi syndrome, a kidney tube disorder
  • Breakdown of muscle (rhabdomyolysis)
  • Some blood cancers and bone marrow disorders
  • Lesch-Nyhan syndrome, a rare inherited condition

What can help

  • Ask your clinician how your diet and fluids could be affecting the amount of uric acid in your urine
  • Ask whether your urine pH and urine volume should be looked at alongside this result
  • Ask how much fluid is right for you if you have had kidney stones

Usual ranges

What labs print as the reference range, by who was tested. Ranges differ a little between labs, so the range on your own report is the one your result is judged against.

For adults: 250–750 mg/24 h. Source: ARUP Laboratories, MedlinePlus Medical Encyclopedia (NIH National Library of Medicine), Jornal Brasileiro de Nefrologia, Mayo Clinic Laboratories (via the testcatalog.org mirror).

If this applies to you

Uric Acid (24h Urine) means a little more for some people. Open the one that fits you.

Gout

Some people are offered a 24-hour urine uric acid test. The ACR 2020 guideline conditionally recommends against checking urine uric acid when choosing or using medicines that help the kidneys clear urate.

Blood tests for gout

What can affect your result

  • Diet, especially purine-rich foods
  • How complete the 24-hour collection is
  • Kidney function
  • Aspirin, gout medicines, anti-inflammatory pain medicines, water pills, alcohol and vitamin C
  • X-ray dye and contrast
  • Sex: Mayo's interval for men is wider than for women
  • Missed urine or a collection that runs short or long changes the total. Labs often check urine creatinine to judge whether the collection was complete.
  • X-ray dye and contrast affect uric acid results. Mayo asks you to wait at least 1 day after a kidney X-ray with dye or a CT scan with contrast, and 7 days after a bile duct X-ray (cholangiography), before you start collecting.
  • Collect before taking tablets for a gallbladder X-ray, otherwise wait 7 days (Mayo).
  • MedlinePlus lists aspirin, gout medicines, anti-inflammatory pain medicines (NSAIDs), water pills, alcohol and vitamin C as things that can change the result. Do not stop any medicine without asking your clinician.
  • A diet high in purines raises uric acid in the urine, so eat as you normally do unless told otherwise.
  • Mayo requires a urine pH of 4.5 to 8. A pH above 8 means bacteria have grown in the sample and the test is canceled. Do not try to adjust the pH yourself.

A full 24-hour collection. Empty your bladder at a set time and discard that urine, then collect every urine for 24 hours, including the first urine at the same time the next morning. Keep it refrigerated or use the preservative your lab provides. Stone work-ups ask for your usual diet. Shows what you excreted over the 24 hours you collected, so it can shift from day to day with diet and fluids.

When to talk to a clinician

Seek care promptly for severe pain in your side or back, especially with nausea, fever, blood in your urine or trouble passing urine, whatever this result says. A sudden, hot, swollen, painful joint is another reason to be seen soon.

Questions you could ask

  • Should we repeat this 24-hour collection, and when?
  • What is my urine pH, and does it matter for my stone or gout risk?
  • Could my diet or any of my medicines be adding to this number?
  • Was my collection complete?
  • Could my kidney function explain this result?

Questions people ask

Why does my lab's range differ from what I read online?

Ranges for 24-hour uric acid depend on diet and on the lab. ARUP and MedlinePlus list 250–750 mg/24 h for adults, while Mayo Clinic Laboratories prints 250–750 for women and 200–1,000 for men. Use the range on your report.

Does a high 24-hour uric acid mean I will get gout?

Not necessarily. Gout is tied mainly to the uric acid level in your blood, while this test measures how much leaves in your urine. A high urine amount can add to kidney-stone risk, and your clinician reads it with your blood level, urine pH and history.

How do I collect a 24-hour sample correctly?

Empty your bladder into the toilet at a set time and note it. Then collect all your urine in the container for the next 24 hours, keeping it cold or using the preservative your lab gives you, and add your first urine at the same clock time the next morning. Follow your lab's instructions exactly.

Show the science and sources

Units

  • 1 mg/24 h = 1 mg/24 h
  • 1 mg/24 h = 0.005948 mmol/24 h
  • 1 mg/24 h = 5.948 µmol/24 h
  • 1 mg/24 h = 0.001 g/24 h

Open the Uric Acid (24h Urine) unit converter

Is a change real?

Uric Acid (24h Urine) naturally varies about 16.8% from test to test in the same healthy person. Between two results from the same lab, a rise of 68% or more, or a fall of 40% or more, is unlikely to be day-to-day noise or lab variation (95% reference change value). Source: Desirable Biological Variation Database specifications, 2014 update (Minchinela J, Ricos C, et al.; the 'Ricos database', a compilation of median published CVI/CVG).

For clinicians and researchers

Urate is measured by a uricase method (Mayo lists uricase for its 24-hour uric acid within the supersaturation profile; ARUP lists quantitative spectrophotometry). ARUP, MedlinePlus and the Brazilian Society of Nephrology (2025) give 250–750 mg/day for adults, and ARUP states that no interval is established for a random urine. Mayo reports 250–750 mg/24 h for women but a wider 200–1,000 mg/24 h for men 18 and older, with no values established under 18. In stone care, hyperuricosuria is commonly defined as more than 800 mg/day in men and more than 750 mg/day in women (Ng 2021, and the Brazilian guideline's action level). The Brazilian guideline adds that uricosuria matters mainly for uric acid stone disease and should be read with 24-hour urine pH. Uric acid stone risk factors are urinary pH below 5.5, low urine volume and hyperuricosuria, alone or together (Ng 2021). Excretion depends on purine and protein intake, so the guideline asks for collections on a usual diet, free of urinary infection, and suggests creatinine to judge collection adequacy. Mayo requires a preservative (diazolidinyl urea) or refrigeration for the whole collection, a pH of 4.5–8, and rejects samples above pH 8 as bacterially contaminated. LOINC offers mass per time (3087-4, used by Mayo), moles per time and mass per volume variants; this entry stores mass or moles per 24 hours only.

LOINC 3087-4 (primary), 14935-1, 21587-1. Specimen: urine-24h.

Sources

  1. SUP24 - Supersaturation Profile, 24 Hour, Urine, Mayo Clinic Laboratories (via the testcatalog.org mirror)
  2. Uric Acid, Urine (test 0020481), ARUP Laboratories
  3. Uric acid urine test, MedlinePlus Medical Encyclopedia (NIH National Library of Medicine)
  4. Brazilian Guidelines on evaluation and clinical management of Nephrolithiasis: Brazilian Society of Nephrology, Jornal Brasileiro de Nefrologia (2025)
  5. Medical evaluation and pharmacotherapeutical strategies in management of urolithiasis, Therapeutic Advances in Urology (2021)
  6. Uric acid (PubChem CID 1175), PubChem (NIH National Library of Medicine)

AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.

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