A uric acid test measures how much uric acid is in your blood or urine. It’s used to help diagnose or monitor gout, kidney stones, kidney disease, and certain complications of cancer treatment. Your body produces uric acid as a waste product when it breaks down purines, compounds found naturally in your cells and in foods like red meat, organ meats, and shellfish. Normally, your kidneys filter uric acid out of your blood and pass it into your urine. When that system falls out of balance, uric acid levels rise or fall in ways that signal specific health problems.
How Your Body Produces Uric Acid
Uric acid is the final product of purine metabolism in humans. Every time your body recycles old cells or digests purine-rich foods, it breaks those purines down through a chain of enzymatic reactions that ends with uric acid. Your liver handles most of this processing, and your kidneys are responsible for filtering roughly 70% of the uric acid out of your bloodstream. The rest leaves through your digestive tract.
Problems crop up in two ways: your body either produces too much uric acid, or your kidneys can’t clear it fast enough. Either scenario leads to a buildup in the blood, a condition called hyperuricemia. Less commonly, uric acid levels drop too low, which can point to liver disease or certain inherited conditions.
Normal Ranges for Adults and Children
Uric acid is measured in milligrams per deciliter (mg/dL) from a standard blood draw. The typical reference ranges are:
- Adult men: 4.0 to 8.5 mg/dL
- Adult women: 2.7 to 7.3 mg/dL
- Children: 2.5 to 5.5 mg/dL
Women generally have lower levels because estrogen helps the kidneys excrete uric acid more efficiently. After menopause, levels tend to rise and approach those seen in men. A result above or below these ranges doesn’t automatically mean something is wrong, but it does prompt your doctor to look more closely at what’s going on.
Gout Diagnosis and Monitoring
Gout is the condition most commonly associated with uric acid testing. It develops when uric acid crystallizes in a joint, triggering sudden, severe inflammation, most often in the big toe. A blood test can reveal whether your uric acid levels are elevated, which supports a gout diagnosis alongside your symptoms and physical exam findings.
The relationship between uric acid levels and gout is not perfectly straightforward, though. Some people have high uric acid levels for years and never develop gout. Others experience classic gout flares while their blood levels appear normal, sometimes because uric acid has already moved out of the blood and into the joints. That’s why doctors don’t rely on the blood test alone. They use it alongside symptom history and sometimes joint fluid analysis to confirm the diagnosis. Once you’re being treated for gout, periodic uric acid testing helps track whether treatment is keeping levels low enough to prevent future flares and crystal deposits.
Kidney Stones and Kidney Disease
High uric acid is one of the known causes of kidney stones. When there’s too much uric acid in your urine, it can crystallize and form hard deposits in your kidneys or urinary tract. A uric acid urine test, which typically involves collecting all your urine over a 24-hour period, helps determine whether uric acid is behind recurrent stones. If you already have gout, your doctor may order this urine test to monitor your ongoing risk for stone formation.
The test also provides a window into overall kidney function. When your kidneys are damaged or diseased, they lose the ability to filter uric acid efficiently, causing blood levels to climb. At the same time, urine levels may drop because the kidneys simply aren’t excreting enough. This pattern, high in the blood and low in the urine, can be an early signal of kidney trouble. In severe cases, persistently high uric acid can itself contribute to kidney failure, creating a cycle where the problem and its cause reinforce each other.
Blood Test vs. Urine Test
There are two versions of the uric acid test, and they answer different questions. A blood test (drawn from a vein in your arm) tells you how much uric acid is circulating in your bloodstream right now. It’s the standard test for evaluating gout, kidney disease, and general metabolic health.
A urine test, usually a 24-hour collection, measures how much uric acid your kidneys are actually clearing. Doctors order this one when they need to figure out whether high blood levels are caused by overproduction of uric acid or by the kidneys failing to excrete enough. This distinction matters for treatment decisions. The urine test is also the go-to choice when kidney stones are the primary concern, since it directly shows how much uric acid is concentrating in your urinary tract.
Monitoring During Cancer Treatment
Uric acid testing plays a critical role during chemotherapy. When cancer treatment kills large numbers of cells quickly, those dying cells dump their contents into the bloodstream all at once. This flood of cellular debris includes a surge of purines, which get converted into uric acid faster than the kidneys can handle. The result is a dangerous condition called tumor lysis syndrome.
In tumor lysis syndrome, uric acid levels spike alongside potassium and phosphate, overwhelming the kidneys and potentially causing kidney failure, heart rhythm problems, seizures, and in severe cases, cardiac arrest. It’s considered a medical emergency. Doctors monitor uric acid levels closely before, during, and after chemotherapy, particularly in cancers with high cell turnover like certain leukemias and lymphomas, to catch the syndrome early and intervene before organ damage occurs.
Uric Acid in Pregnancy
Uric acid sometimes comes up in the context of preeclampsia, a pregnancy complication involving high blood pressure and organ stress. Because uric acid reflects oxidative stress and kidney function, it was historically used as a marker for preeclampsia severity. However, the American College of Obstetricians and Gynecologists does not recommend using uric acid to diagnose preeclampsia, and studies on whether it reliably predicts complications for mother or baby have produced conflicting results.
There is one exception: in pregnancies complicated by chronic high blood pressure, a baseline uric acid level can help doctors rule out certain causes of secondary hypertension and assess whether there’s already some organ damage. Outside that specific scenario, uric acid testing has limited value in routine prenatal care.
What Low Uric Acid Means
Most people worry about high levels, but abnormally low uric acid (below 2 mg/dL) also warrants attention. Low levels can result from decreased production, often tied to liver disease, since the liver is where most purine processing happens. Certain medications that treat gout work by blocking the enzyme responsible for producing uric acid, which can push levels very low as an expected side effect.
Rare inherited conditions can also cause extremely low levels, sometimes below 1 mg/dL. In some of these conditions, the body produces excess xanthine (a purine precursor) instead of uric acid, which can lead to a different type of kidney stone. People with inherited forms of low uric acid may also face a higher risk of acute kidney injury. Low urine uric acid, on its own, can be a sign that the kidneys aren’t functioning properly.
What Can Affect Your Results
Several factors can shift your uric acid levels independently of any disease. Alcohol, particularly beer, raises uric acid by increasing purine intake and reducing kidney excretion at the same time. Dehydration concentrates uric acid in the blood. High-purine diets (heavy on red meat, organ meats, and certain seafood) can temporarily elevate levels, while low-purine diets and adequate hydration tend to bring them down. Certain medications, including some diuretics (water pills) and low-dose aspirin, can raise uric acid as a side effect. Let your doctor know what you’re taking and drinking so they can interpret your results in context.