A 24 hour urine uric acid test measures how much urate your kidneys clear in a full day. In the biomarker guides we publish here, this is the test readers most often mistake for the ordinary blood uric acid result on an annual panel. The two tests report different quantities and belong to different workups.
The Verdict
What the 24 Hour Urine Uric Acid Test Measures
The test reports the total mass of urate leaving your body in urine across one full day, in milligrams per 24 hours. The laboratory does not measure that directly. It measures the urate concentration in a small aliquot drawn from your well-mixed collection, then multiplies by the total volume you recorded on the jug. ARUP runs it by quantitative spectrophotometry and bills it under Current Procedural Terminology (CPT) code 84560, the code for uric acid measured in a source other than blood.
The recorded volume therefore matters as much as the chemistry. A wrong volume leaves the concentration correct and the reported milligrams per day wrong.
A rate answers something a concentration cannot. Serum urate sits at the balance point between how much urate you make and how much your kidneys clear. One high blood number is therefore compatible with heavy production or with poor clearance. The 24 hour collection separates production from clearance, at the cost of a day spent carrying a jug.
What Counts as a Normal Result
ARUP Laboratories publishes 250 to 750 mg per day as its adult reference interval for urine uric acid on a 24 hour collection. Read your own report's printed band first, since laboratories derive their intervals from their own populations and assays.
| Result | How it is classified | What follows |
|---|---|---|
| Below 250 mg per day | Under ARUP's published interval | Usually a low-purine diet, a urate-lowering drug already working, or reduced kidney clearance. Read it next to your eGFR before reading it as anything else. |
| 250 to 750 mg per day | Inside ARUP's published interval | The ordinary result. It does not rule out a stone risk, because urine volume, pH and calcium all sit on the same report and any of them can be the problem. |
| 750 to 800 mg per day | Above ARUP's ceiling, below the AUA action threshold | Your report shows an out-of-range arrow and the kidney-stone guideline still does not prescribe anything for it. |
| Above 800 mg per day | Hyperuricosuria as the AUA defines it | The number that changes management, and only in specific stone types. In recurrent calcium oxalate stone formers with normal urine calcium, the AUA says clinicians should offer allopurinol. |
ARUP's upper limit is 750 mg per day and the American Urological Association's hyperuricosuria threshold is 800 mg per day. The two numbers answer different questions, 50 mg apart. A result of 780 arrives with a high flag on the report and no guideline action attached to it.
Neither source is wrong. A laboratory interval describes where the middle of a reference population sits, and a guideline threshold marks the level at which treatment changed outcomes in a trial. The AUA cites a prospective randomised controlled trial behind its 800 mg figure. In that trial allopurinol reduced recurrent calcium oxalate stones in people with hyperuricosuria and normal urinary calcium. That makes 800 mg a treatment cut-point rather than a biological boundary.
Why This Test Belongs to the Kidney Stone Workup
Urine uric acid is one line of a nine-part panel, never a standalone order. AUA Statement 6 specifies one or two 24 hour urine collections obtained on a random diet. The minimum analyte list is total volume, pH, calcium, oxalate, uric acid, citrate, sodium, potassium and creatinine. Statement 5 puts that testing at Grade B for high-risk or interested first-time stone formers and for recurrent stone formers.
Two of the other eight lines bear on whether urate can crystallise at all. In uric acid stone formers, AUA Statement 19 puts urine pH ahead of urate output. Urine volume matters on the same collection because it sets how concentrated everything in the urine becomes.
Where the urate number does change treatment, it does so narrowly. AUA Statement 16 is a Grade B Standard. Clinicians should offer allopurinol to patients with recurrent calcium oxalate stones who have hyperuricosuria and normal urinary calcium. The guideline sets hyperuricosuria at excretion above 800 mg per day, and adds that a raised blood urate is not a required criterion for the offer. A blood urate and a urine urate are doing separate jobs, and the guideline treats them that way.
For stones made of uric acid itself, the same guideline points the other way. Statement 19 says clinicians should not routinely offer allopurinol as first-line therapy for uric acid stones. Most people with uric acid stones have low urinary pH rather than hyperuricosuria as the main risk factor. For those stones, potassium citrate to raise urine pH toward 6.0 comes first. Statement 12 adds a dietary line: people with uric acid stones, or calcium stones with relatively high urinary uric acid, should be counselled to limit non-dairy animal protein.
What the Gout Guidelines Say About Ordering It
The 2020 American College of Rheumatology gout guideline conditionally recommends against checking urinary uric acid for patients considered for or receiving uricosuric treatment. The panel's stated reason was practical. A 24 hour collection and nomogram-based testing are both hard to do well and both are affected by diet. Against a very low level of evidence, the panel judged that this negates the utility of such testing.
That recommendation is worth knowing before you ask for the test. The teaching it replaced sorted gout patients into overproducers and underexcretors by urine collection. That sorting no longer guides the choice of urate-lowering drug in the ACR's framework.
Who Should Not Order a 24 Hour Urine Uric Acid Test
Anyone whose actual question is "do I have gout" should skip this test. MedlinePlus lists the blood uric acid test, usually alongside a synovial fluid analysis, as the pair used to help diagnose gout. A urate crystal seen in joint fluid settles the diagnosis, and a day of urine collection does not.
- A raised serum urate on a routine panel, with no stones and no attacks. No result from the collection changes what happens next. Track the blood urate alongside a metabolic panel instead, since raised urate travels with insulin resistance more often than with diet.
- Anyone about to start a uricosuric drug. The ACR recommendation covers this case directly. Ask the prescribing clinician what they plan to monitor instead.
- Anyone who cannot realistically complete the collection. A partial jug produces a falsely low number that reads as reassurance. Ask about scheduling the collection for a day you are at home, and see how to collect the sample before you start.
- Anyone comparing consumer longevity panels. No direct-to-consumer platform we track runs a 24 hour stone panel. The 24 hour stone panel comes from a clinician, and the platform reviews compare what the consumer panels do cover.
What Would Change Our Answer
Two developments would move this test from narrow to routine. The first is a validated spot urine urate-to-creatinine ratio accurate enough for stone-risk decisions. A ratio like that would remove the jug and most of the collection error with it. The second is a revision of the ACR gout guidance restoring urinary urate to the drug-choice pathway. The 2020 panel left that door open by grading the evidence very low rather than negative.
Until one of those two changes happens, the test earns its place in a stone workup and almost nowhere else.
What Can Spoil the Result
- Missed voids. The failure the creatinine check exists to catch. A short collection reports fewer milligrams than your kidneys cleared.
- An unusual eating day. Purine intake moves the number, and the AUA asks for a random diet for that reason.
- Wrong preservative or pH. ARUP requires the urine pH be adjusted above 8.0 with 5 percent sodium hydroxide, because urate precipitates out of acidic urine and stops being measurable in the aliquot.
- Room-temperature storage. ARUP requires refrigeration throughout the collection.
- Medicines you did not mention. Diuretics, allopurinol and salicylates all change urate handling.
Each of these is fixable in advance, and the sequence for doing so is in our guide to collecting a 24 hour urine sample for uric acid.
Which Situations Justify the Test
| Your situation | Order a 24 hour urine uric acid? | Why |
|---|---|---|
| Recurrent calcium oxalate stones | Yes, as one line of a full stone panel | Hyperuricosuria above 800 mg per day with normal urine calcium is the finding that triggers an allopurinol offer under AUA Statement 16. |
| A first stone, high risk or wants the workup | Yes | AUA Statement 5 puts metabolic testing at Grade B for high-risk or interested first-time stone formers as well as recurrent ones. |
| Uric acid stones confirmed on stone analysis | Yes, but the pH matters more | Most uric acid stone formers have acidic urine rather than high urate output, so potassium citrate to raise urine pH toward 6.0 comes first. |
| Gout, before starting a uricosuric drug | No | The ACR conditionally recommends against checking urinary uric acid in exactly this situation. |
| A high blood urate found on a routine panel, no symptoms | No | Nothing on the 24 hour result changes what happens next. A serum urate above range without gout or stones is not treated on the number alone. |
| Suspected inherited purine disorder in a child | Specialist territory | Paediatric intervals differ from adult ones and the workup runs well past a single urate measurement. |
If you form stones and have never had a metabolic workup, ask your clinician for the full AUA stone panel rather than a lone 24 hour urine uric acid test. The urate line only becomes interpretable next to the other eight analytes.
Frequently Asked Questions
What is a normal 24 hour urine uric acid level?
ARUP Laboratories publishes a reference interval of 250 to 750 mg per day for a 24 hour urine uric acid collection. Your own report may print a slightly different band, because each laboratory derives its interval from its own reference population and assay. Read your result against the range printed on your report first. The number is also diet-sensitive by design. The American Urological Association asks for the collection on a random diet, so the result reflects how you normally eat. A purine-free rehearsal day produces a number that will not repeat.
What does a high 24 hour urine uric acid mean?
It means your kidneys are putting out more urate per day than the reference population does, which raises the concentration of urate available to crystallise in urine. The American Urological Association defines hyperuricosuria as urinary uric acid excretion above 800 mg per day. That threshold matters in one setting above all: recurrent calcium oxalate stones with normal urinary calcium, where the AUA gives a Grade B recommendation that clinicians should offer allopurinol. High urinary urate on its own, with no stone history, is not a diagnosis and is not treated.
Is 800 mg of uric acid in 24 hours high?
Yes, 800 mg per day sits above ARUP Laboratories' upper limit of 750 mg and at the American Urological Association's definition of hyperuricosuria. Between 750 and 800 mg per day there is a real gap: your lab report will flag the result as high while the stone guideline does not act on it. That gap is not an error in either source. A laboratory reference interval describes the middle of a healthy population. A guideline threshold marks where treatment changed outcomes in a trial. Our guide to normal versus optimal ranges draws the same distinction for every marker.
What does a low uric acid in 24 hour urine mean?
A result under 250 mg per day usually has one of three explanations. Purine intake was low during the collection, a urate-lowering drug such as allopurinol is already reducing production, or kidney clearance is reduced. The third is the one to rule out, because a low urinary output alongside a high blood urate indicates reduced excretion rather than overproduction. Read the result next to your eGFR and the creatinine on the same collection before reading it as a dietary finding.
Do I need to fast for a 24 hour urine uric acid test?
No, and fasting would defeat the purpose. The American Urological Association specifies that metabolic stone testing be done on a random diet, meaning you eat as you normally do for the whole collection day. A collection done on an unusually purine-free day produces a low number that describes a day you do not usually live. Follow whatever instruction the ordering clinician gives about medicines, since some urate-lowering and diuretic drugs change the result directly.
What is the CPT code for a 24 hour urine uric acid test?
ARUP Laboratories bills urine uric acid under CPT code 84560, which covers uric acid measured in a source other than blood. The blood version is CPT 84550. Seeing 84560 on a bill alongside 82570 for urine creatinine is normal. Creatinine is measured on the same collection to check that the jug covers a genuine 24 hours.
Can a 24 hour urine uric acid test diagnose gout?
No. Gout is diagnosed from a urate crystal seen in joint fluid, supported by the blood urate, and MedlinePlus lists synovial fluid analysis alongside the blood test for that purpose. The 2020 American College of Rheumatology gout guideline goes further. It conditionally recommends against checking urinary uric acid in patients considered for or receiving uricosuric treatment. Its stated reasons were the difficulty of the collection and its sensitivity to diet, against a very low level of evidence. If the question is gout, ask about joint aspiration and a serum urate rather than a urine jug.
How often should the test be repeated?
For someone on stone-prevention treatment, the American Urological Association advises a single 24 hour urine specimen annually after the initial follow-up, or more often depending on stone activity. The point of the repeat is to see whether the treatment moved the number and whether you are still taking it. Outside stone prevention there is no schedule, because there is no result that would change management on its own.