Uric acid
Blood test
Also known as: Urate, Serum urate
- Below the high range Below 6.8 mg/dL
- High (hyperuricemia) 6.8 mg/dL and above
Units and reference ranges differ between labs.
Cutoffs: American College of Rheumatology, Gout Guideline 2020
This test measures uric acid, also called urate, in your blood. Too much can form crystals in the joints, and those crystals cause gout. Most people with high uric acid never get gout.
What it tells you
- Above a certain level, uric acid can form crystals. Crystals in a joint, or in a lump called a tophus, are what define gout.
- The American College of Rheumatology defines high uric acid as 6.8 mg/dL or more.
- Below 6 mg/dL is a treatment goal only for people taking medicine to lower uric acid for gout. It is not a goal for everyone.
- High uric acid without gout is usually not treated with medicine. The guideline advises against it, even with kidney disease, heart disease or high blood pressure.
- Gout is diagnosed from symptoms or from finding crystals, not from a blood level alone.
- High uric acid goes with heart and kidney disease. But genetic studies and trials of lowering it have not shown that it causes them.
What can throw it off
- A level drawn during a gout flare may not show the usual level. It is best rechecked more than 4 weeks after the flare starts.
- Water pills (thiazide and loop diuretics) raise it. In one study, starting one raised uric acid by about 0.7 mg/dL.
- Losartan and fenofibrate lower it a little. Low-dose aspirin can affect it, but the guideline advises against stopping aspirin for that reason.
- Alcohol raises it. People who cut back or stopped drinking had levels about 1.6 mg/dL lower.
- Fructose and sugary drinks raise it. A large amount of fructose can raise it 1 to 2 mg/dL within two hours.
- Weight loss lowers it. In a large trial, tirzepatide lowered it by about 0.7 to 0.95 mg/dL, mostly through weight loss.
- Very fast weight loss after weight-loss surgery can raise it for a short time.
- Changes to purine-rich foods move it only slightly. Vitamin C changed it too little to matter in two small trials.
Evidence
Predicting gout
In 18,889 adults followed for about 11 years, the 15-year chance of gout was 1.1% below 6 mg/dL and 49% at 10 mg/dL or more. Even at that level, about half did not get gout in 15 years.
Guiding gout treatment
In a UK trial of 517 adults with gout, care that adjusted medicine toward the target got 95% below 6 mg/dL at two years. Only 30% got there with usual care, and flares and tophi also improved. The trial tested a whole care package, not the target alone.
Lowering it to protect heart or kidneys
Across 26 studies, high uric acid was only weakly linked to heart disease once other risks were counted. Genetic studies found no sign that it causes heart disease or diabetes. In trials, lowering it with allopurinol did not slow kidney decline or prevent heart attacks and strokes.
Limits
- High uric acid is not gout. Even at 10 mg/dL or more, about half of people do not develop gout over 15 years.
- A normal level during a flare does not rule out gout.
- Below 6 mg/dL is a treatment goal for gout, not a general goal.
- The link with heart and kidney disease is not a reason to treat. Trials of lowering it in people without gout found no benefit.
- It moves with recent diet, alcohol, water pills and weight change. One result is a snapshot.
References
This page is for education only. It is not medical advice. Decisions about any treatment belong with a physician who knows your history.