The uric acid blood test measures a concentration and the urine test measures a rate. We see readers treat them as two ways of running one test. They are ordered by different specialists, for different questions, and a normal blood result does not tell you what the urine result will be.
The Verdict
Side by Side
Both tests measure the same molecule by the same chemistry. ARUP Laboratories runs each by quantitative spectrophotometry. Everything that separates them comes from the specimen.
| Criterion | Blood uric acid | 24 hour urine uric acid |
|---|---|---|
| What it reports | Urate concentration in blood at one moment | Urate mass leaving the body over one day |
| Units | mg/dL | mg per 24 hours |
| Typical published range | Roughly 3.5 to 7.2 mg/dL | 250 to 750 mg per day (ARUP) |
| CPT code | 84550 | 84560 |
| Specimen | One tube, drawn in minutes | Every void for 24 hours, refrigerated, pH raised above 8.0 |
| Diet sensitivity | Moves with a recent purine-heavy meal or alcohol | Reflects the whole collection day, and the AUA asks for a random diet for that reason |
| Used to diagnose gout | Yes, with joint fluid analysis | No |
| Used in the kidney stone workup | Sometimes, as background | Yes, as one of nine required lines |
| What a raised result triggers | Nothing on its own without gout or stones | Above 800 mg per day in recurrent calcium oxalate stones, an allopurinol offer |
| Verdict | The first test for gout and for tracking a known urate problem | The stone test, ordered inside a full metabolic panel |
Concentration Against Rate
A serum urate result describes the balance point between how much urate your body produces and how much your kidneys clear. Purines from your own cells turning over and from food get broken down to urate, and the kidneys handle most of the disposal. A single number therefore reflects both sides at once and cannot separate them.
A 24 hour urine result describes only the disposal side, in milligrams per day. The laboratory measures urate concentration in an aliquot from your mixed collection and multiplies it by the total volume you recorded. ARUP publishes 250 to 750 mg per day as its reference interval for that calculation.
That difference explains the ordering pattern. A rheumatologist asking whether crystals are forming in a joint wants the concentration, because crystallisation depends on how saturated the fluid is. A urologist asking why stones keep forming wants the daily load arriving in the urine, because the daily load determines how concentrated the urine becomes.
Which One Your Question Needs
The right test follows from the question rather than from which sounds more thorough. Six situations cover most of the reasons either test gets ordered.
| Your situation | Which test | Why |
|---|---|---|
| A painful, swollen big toe | Blood, plus joint aspiration | MedlinePlus lists the blood urate alongside synovial fluid analysis for diagnosing gout. Urate can fall into the normal range during an acute attack, so the joint crystal settles the diagnosis. |
| A second kidney stone in three years | Urine, inside the full AUA panel | AUA Statement 6 requires total volume, pH, calcium, oxalate, uric acid, citrate, sodium, potassium and creatinine on the same collection. |
| A high urate on an annual panel, no symptoms | Neither, beyond repeating the blood test | No result from a 24 hour collection changes management here. Read the blood urate alongside triglycerides and fasting insulin instead. |
| Starting a uricosuric drug for gout | Blood only | The ACR conditionally recommends against checking urinary uric acid in patients considered for or receiving uricosuric treatment. |
| Confirmed uric acid stones on stone analysis | Urine, and the pH line matters more than the urate line | AUA Statement 19 says most uric acid stone formers have low urine pH rather than hyperuricosuria as the main risk factor. |
| Monitoring urate during cancer treatment | Blood | MedlinePlus lists monitoring during chemotherapy as a blood-test use. A day-long average would arrive too late to guide treatment. |
When to Choose the Blood Test
Choose the blood test whenever the question is about urate itself rather than about stones. It aids the diagnosis and monitoring of gout alongside joint fluid analysis. MedlinePlus lists monitoring during cancer chemotherapy as a further use. It is one tube, one billed line, and on many annual panels it is already there.
One caveat governs how you read it. Urate frequently falls during an acute gout attack, as our uric acid blood test guide sets out. A level drawn while a joint is inflamed can mislead, and it is usually repeated once the attack settles.
When to Choose the 24 Hour Urine Test
Choose the urine collection when you form kidney stones and want to know why. AUA Statement 5 puts metabolic testing at Grade B for recurrent stone formers and for high-risk or interested first-time stone formers. Statement 6 then specifies one or two 24 hour collections on a random diet. The minimum analyte list is total volume, pH, calcium, oxalate, uric acid, citrate, sodium, potassium and creatinine.
The urate line changes treatment in one defined case. AUA Statement 16 is a Grade B Standard. Clinicians should offer allopurinol to patients with recurrent calcium oxalate stones who have both hyperuricosuria and normal urinary calcium. The guideline sets hyperuricosuria at urinary uric acid excretion above 800 mg per day. It also notes that a raised blood urate is not a required criterion for that offer. That is the plainest evidence the two tests are not substitutes.
Why the Gout Guideline Advises Against the Urine Test
The 2020 American College of Rheumatology gout guideline conditionally recommends against checking urinary uric acid for patients considered for or receiving uricosuric treatment. Its voting panel gave a practical reason. A 24 hour collection and nomogram-based testing are both affected by diet, which the panel said negates their utility against a very low level of evidence.
Before the 2020 guideline, gout patients were sorted into overproducers and underexcretors by 24 hour collection. That framing still circulates, which is one reason the urine test keeps surfacing in gout searches. If a clinician does propose it for gout, that recommendation is the thing to ask them about.
One Tube Against One Day of Collecting
The chemistry is the same. The effort is not, and effort decides how many collections get completed. The blood test takes minutes and needs no preparation beyond whatever fasting instruction your laboratory gives.
The 24 hour collection is a genuine imposition. You discard the first void, collect every void after it for exactly 24 hours, keep the container refrigerated or on ice throughout, and record the total volume. ARUP additionally requires the urine pH be adjusted above 8.0 with 5 percent sodium hydroxide before an aliquot is taken, because urate precipitates in acidic urine and stops being measurable.
A missed void makes the reported milligrams per day too low. A low number reads as reassurance, which is the worst failure mode for a test used to decide whether to prevent stones. Creatinine measured on the same collection exposes a short collection. The full sequence, including what to do if you miss a void, is in our guide to collecting a 24 hour urine sample for uric acid.
Who This Comparison Does Not Serve
- Anyone shopping consumer longevity panels. No direct-to-consumer platform we track sells a 24 hour stone panel. Serum urate appears on some of them, and the platform reviews compare what those panels include.
- Anyone hoping a home strip replaces either test. The MedlinePlus urinalysis entry lists the dipstick examples as red blood cells, glucose, protein, pH, ketones, bilirubin and specific gravity, and uric acid is not among them. Ask the clinician managing your stones whether tracking urine pH with strips fits their plan.
- Parents of a child with a suspected purine disorder. Paediatric reference intervals differ from adult ones and the workup runs well past urate. That belongs with a paediatric metabolic specialist.
- Anyone with a single raised urate and no symptoms. Neither test earns its place yet. Retest the blood urate and read it beside a metabolic panel, since raised urate travels with insulin resistance more often than with diet.
What Would Change Our Answer
A revision of the ACR gout guidance would change it most. The 2020 panel graded the evidence very low rather than negative. A trial linking urinary urate to a better drug choice would put the urine test back on the gout side.
A validated spot urine urate-to-creatinine ratio would change the stone side, for the reasons set out in what a 24 hour urine uric acid result means. Neither has happened, so the split between the two tests holds.
Take your actual question to a clinician. If the problem is a painful joint, ask for a serum urate and a joint aspiration. If the problem is stones, ask for the full AUA stone panel rather than a lone urine uric acid test.
Frequently Asked Questions
Is a uric acid test blood or urine?
Both exist and they are ordered for different reasons. The default, and the one on almost every annual panel, is the blood test: ARUP Laboratories runs it as Uric Acid, Serum or Plasma under CPT code 84550. The urine version is a 24 hour collection billed under CPT 84560, and it is ordered mainly inside a kidney-stone metabolic workup. If someone told you to get "a uric acid test" with no further instruction, they almost certainly meant the blood draw.
What is the difference between a uric acid blood test and a urine test?
The blood test reports a concentration and the urine test reports a rate. A serum urate of 8.1 mg/dL says how much urate is circulating at the moment the needle went in. A 24 hour urine result of 620 mg per day says how much your kidneys cleared across a whole day. The blood number sits at the balance point between production and clearance, so it cannot tell you which side is responsible. The urine collection separates them, which is the whole reason it exists.
Can a urine test detect uric acid?
Yes, and ARUP Laboratories measures it by quantitative spectrophotometry on an aliquot drawn from a well-mixed 24 hour collection. Two handling rules keep this a laboratory test. Urate precipitates out of acidic urine, so ARUP requires the sample pH be raised above 8.0 with 5 percent sodium hydroxide, and the collection must stay refrigerated throughout. A home dipstick cannot substitute for the collection. The MedlinePlus urinalysis entry does not list uric acid among the dipstick measurements.
Which uric acid test is used to diagnose gout?
The blood test, and even then it does not settle the diagnosis alone. MedlinePlus lists the blood uric acid test as an aid to diagnosing gout, usually done together with a synovial fluid analysis. Urate crystals seen in fluid drawn from the joint are the confirming finding. Serum urate frequently falls during an acute attack, sometimes into the normal range, so a normal blood result taken while a joint is inflamed does not exclude gout. The 2020 American College of Rheumatology guideline conditionally recommends against checking urinary uric acid in patients considered for or receiving uricosuric treatment.
Can both tests be normal and something still be wrong?
Yes, and the combination that catches people out is a high blood urate with a normal urine output. Underexcretion is the usual mechanism, so the normal urine number is the expected finding rather than reassurance. Read the two together with kidney function on the same report, and see our eGFR guide for the clearance side.
Do I need to fast for either uric acid test?
Practice varies for the blood test and no fast is wanted for the urine collection. Many laboratories ask for a fast of several hours before a blood urate, as our uric acid blood test guide sets out. A recent purine-heavy meal or alcohol moves the result. The instruction also depends on what else is on the panel, so follow the one your laboratory gives. For the 24 hour urine test the American Urological Association asks specifically for a random diet. That means eating as you normally do, because the collection is meant to measure an ordinary day.
Are urine uric acid test strips accurate?
A urinalysis dipstick does not report the numbers either of these tests produces. Uric acid is not among the dipstick parameters the MedlinePlus urinalysis entry lists. A dipstick does report urine pH, and the AUA identifies low urine pH as the predominant risk factor in uric acid stone formers. Even that reading is coarse next to a laboratory pH on a proper collection. If you want a urate number, it comes from a laboratory. If you want to track pH between clinic visits, ask the clinician managing your stones whether strips fit their plan.
Which uric acid test costs more?
The 24 hour urine test, because it is almost never billed as a single line. It arrives as part of the nine-analyte AUA metabolic panel, so the bill carries urate under CPT 84560 alongside creatinine under 82570 and the seven other analytes. The blood test under CPT 84550 is one line, and it is frequently already inside a broader panel you are having anyway. Neither ARUP list price is public, so ask the ordering laboratory for the price of the full stone panel rather than the urate line.