Key Takeaways
- Serum urate above about 6.8 mg/dL is supersaturated and can form crystals; the higher it stays above this point, the higher the gout risk. [1][3]
- Hyperuricemia is commonly defined as a serum urate at or above 7.0 mg/dL, but many people with mild hyperuricemia never develop gout. [2][3]
- Serum urate can be normal during an acute flare, so a normal level does not rule out gout when the story fits. [4]
- Gout risk rises steeply with urate: in one cohort, annual gout incidence was 0.1 percent below 7.0 and 4.9 percent at 9.0 mg/dL or higher. [3]
- The treatment target on urate-lowering therapy is below 6 mg/dL, and below 5 mg/dL in tophaceous disease. [1]
- Serum urate is influenced by kidney function, medicines such as diuretics, alcohol, weight, and even the acute flare itself. [5]
What Is Uric Acid (Urate)?
Uric acid is the end product of purine breakdown in the body. Purines come from both the food we eat and normal cell turnover, and most of the body's urate is cleared by the kidneys. In blood, uric acid exists mostly as urate, and the two terms are used interchangeably in everyday talk.[5]
Urate itself is not the enemy; every person has a level. The problem is when it stays high enough, long enough that it begins to crystallize.[1] The biology of gout is really about the solubility of monosodium urate, not about a toxic chemical level in the ordinary sense.
How Uric Acid Is Measured
Uric acid is measured on a routine blood test usually as part of a metabolic panel or a specific urate test. Results are reported in milligrams per deciliter (mg/dL) in the United States and millimoles per liter elsewhere. The test is inexpensive, widely available, and useful both to confirm a high level and to monitor urate-lowering treatment.[1]
It is important to know when the level was drawn. Serum urate often drops during the first day or two of an acute flare, which is why a normal reading taken in the middle of an attack can be misleading.[4] When the diagnosis is uncertain, repeating the level once the flare has settled gives a truer picture.
Reference Ranges and the 6.8 Threshold
Typical laboratory reference ranges are about 2.4 to 6.0 mg/dL in women and 3.4 to 7.0 mg/dL in men, though ranges vary by lab.[2] The physical constant that matters most for gout is the saturation point of monosodium urate in body fluids at normal body temperature, roughly 6.8 mg/dL. Above this, crystals can form in and around joints.[1]
This threshold is why the treatment target for gout is set just below it. It is also why "normal" on a lab report is not the same thing as "safe for someone with gout," most gout treatment aims below 6 mg/dL, which is below the top of many normal ranges.[1]
What Counts as High (Hyperuricemia)
Hyperuricemia is commonly defined as a serum urate at or above 7.0 mg/dL (some definitions use above 6.0 in women). In NHANES data from 2015 to 2016, hyperuricemia affected roughly one in five U.S. adults, while gout itself affected about 3.9 percent.[2] The large gap between the two numbers is the key point: most people with a high urate never get gout, and many are never treated for it.[3]
This is why an elevated urate by itself, without gout, is generally watched rather than treated. The 1987 Normative Aging Study showed the dose-response clearly: annual gout incidence was 0.1 percent below 7.0 mg/dL, 0.5 percent from 7.0 to 8.9, and 4.9 percent at 9.0 or above, with a 22 percent five-year cumulative incidence in the highest group.[3]
How High Urate Causes Gout
Gout is not simply a high number on a lab sheet; it is an immune response to monosodium urate crystals that have formed because urate has been supersaturated for long enough. When those crystals form in a joint, the body mounts an intense inflammatory attack, which is what a flare feels like.[1][5] Over the years, untreated crystal deposition can also build up as tophi and erode bone.
This two-step logic, first sustained hyperuricemia, then crystal formation and inflammation, explains the two treatment strategies: lower urate below the saturation threshold to stop new crystals and slowly dissolve old ones, and use anti-inflammatory medicines to quiet a flare in the meantime.[1]
Reading Your Number
| Serum urate | What it suggests |
|---|---|
| Below 6.0 mg/dL | At or below most treatment targets; low gout risk at this level |
| 6.0 to 6.8 mg/dL | Near the saturation threshold; below the common treatment target for gout |
| 6.8 mg/dL and above | Above the solubility threshold; crystals can form |
| 7.0 to 8.9 mg/dL | Hyperuricemia; modestly higher gout risk (0.5 percent per year in one cohort) |
| 9.0 mg/dL and above | Markedly higher gout risk (4.9 percent per year in one cohort) |
These bands are interpretive guidance, not diagnosis. A number alone does not diagnose gout, and a single reading can be shifted by an active flare, a recent meal, alcohol, or medicines.[3][4]
Treatment Targets: Below 6, or Below 5 With Tophi
For people taking urate-lowering therapy, the 2020 ACR guideline recommends a treat-to-target approach with a serum urate target below 6 mg/dL for most people and commonly below 5 mg/dL for those with tophi, to drive crystal dissolution faster.[1] The target is checked periodically and the medication dose adjusted until it is met, then maintained.
| Situation | Urate target |
|---|---|
| Most people on urate-lowering therapy | Below 6 mg/dL |
| Tophaceous gout | Below 5 mg/dL |
| Untreated hyperuricemia without gout | No routine pharmacologic target; usually monitored |
When and How Often to Test
A urate level is part of the initial evaluation for suspected gout, together with the history, examination, and ideally joint-fluid crystal analysis for a first or uncertain presentation.[4] Once urate-lowering therapy begins, the guideline calls for repeat testing to guide dose titration until the target is reached, then periodic checks to confirm it stays there.[1] During a flare, a level drawn early can be falsely normal, so for diagnostic purposes it is often repeated later.[4]
What Raises or Lowers the Number
| Raises urate | Lowers urate |
|---|---|
| Thiazide and loop diuretics | Urate-lowering drugs (allopurinol, febuxostat) |
| Obesity and weight gain | Weight loss |
| Alcohol, especially beer and spirits | Avoiding excess alcohol |
| Sugar-sweetened drinks and fructose | Lower-fat dairy, DASH-style eating |
| Reduced kidney function | Losartan, a blood pressure medicine |
| High-purine meals (organ meats, some seafood) | Adequate hydration |
These influences explain why a single number is only part of the story. A person's urate reflects kidney function, medicines, weight, diet, alcohol, and even genetics.[5] Among blood pressure medicines, diuretics are associated with higher gout risk while losartan is associated with lower risk, which is why medication review matters when urate is persistently high.[5][6]
When Urate Is Too Low
A urate below the reference range (hypouricemia) is usually harmless and does not cause symptoms in most people, though very low levels can occasionally reflect an underlying condition or, rarely, be associated with kidney stones from over-excretion. A clinician can decide whether a low level needs any investigation, but it is generally not a problem to chase.[5]
For people on urate-lowering therapy, the goal is below target but not zero; a comfortably sub-saturation level is what is wanted, not the lowest possible number.[1]
Frequently Asked Questions
A urate of 9.0 mg/dL or higher carries a materially higher gout risk (4.9 percent annual incidence in one cohort) and is usually evaluated for treatment and for kidney health, but it does not by itself mean active gout.[3]
Yes. Serum urate often falls in the first day or two of a flare, so a normal level taken then does not rule out gout. It is often repeated once the flare settles.[4]
Medication is guided by gout burden, not a number alone. The ACR strongly recommends urate-lowering therapy for tophi, radiographic damage, or two or more flares a year, with a serum urate target below 6 mg/dL.[1]
With allopurinol or febuxostat, urate falls within days to weeks, but the dose is typically titrated over weeks to months to reach and hold the target. Diet alone lowers urate more slowly and modestly.[1]
Very high urate (roughly 10 mg/dL or above) sharply increases gout and kidney stone risk and can reflect rapid cell turnover, so it warrants evaluation. The concern is the consequences of sustained elevation, not a single day's number.[3]
They are used interchangeably in practice. Uric acid in blood exists mostly in its ionized form, urate. A serum urate measurement is the same test as a uric acid level.[5]
Fasting is not always required, but levels can vary with meals and alcohol, so follow the ordering clinician's instructions for the most consistent reading.
References
- FitzGerald JD, Dalbeth N, Mikuls T, et al. 2020 American College of Rheumatology Guideline for the Management of Gout. Arthritis Care & Research. 2020;72(6):744-760. doi:10.1002/acr.24180. https://pmc.ncbi.nlm.nih.gov/articles/PMC10563586/
- Chen-Xu M, Yokose C, Rai SK, Pillinger MH, Choi HK. Contemporary Prevalence of Gout and Hyperuricemia in the United States and Decadal Trends: NHANES 2007-2016. Arthritis & Rheumatology. 2019;71(6):991-999. doi:10.1002/art.40807. PMID: 30618180. https://pubmed.ncbi.nlm.nih.gov/30618180/
- Campion EW, Glynn RJ, DeLabry LO. Asymptomatic hyperuricemia. Risks and consequences in the Normative Aging Study. The American Journal of Medicine. 1987;82(3):421-426. doi:10.1016/0002-9343(87)90441-4. PMID: 3826098. https://pubmed.ncbi.nlm.nih.gov/3826098/
- Neogi T, Jansen TL, Dalbeth N, et al. 2015 Gout Classification Criteria: an American College of Rheumatology/European League Against Rheumatism collaborative initiative. Arthritis & Rheumatology. 2015;67(10):2557-2568. doi:10.1002/art.39254. PMID: 26352873. https://pubmed.ncbi.nlm.nih.gov/26352873/
- Kuo CF, Grainge MJ, Zhang W, Doherty M. Global epidemiology of gout: prevalence, incidence and risk factors. Nature Reviews Rheumatology. 2015;11(11):649-662. doi:10.1038/nrrheum.2015.91. PMID: 26150127. https://pubmed.ncbi.nlm.nih.gov/26150127/
- Choi HK, Soriano LC, Zhang Y, Rodríguez LA. Antihypertensive drugs and risk of incident gout among patients with hypertension. BMJ. 2012;344:d8190. doi:10.1136/bmj.d8190. PMID: 22240117. https://pubmed.ncbi.nlm.nih.gov/22240117/