Uric Acid Kidney Stones

Uric acid kidney stones are hard deposits that form when your urine contains too much uric acid and becomes too acidic. Unlike other kidney stones made of calcium, these stones form specifically when urine pH drops below 5.5. At this acidic level, uric acid cannot dissolve properly and begins to crystallize into stones.

These stones can be as small as a grain of sand or grow to the size of a golf ball. They develop in your kidneys but can travel through your urinary tract, causing pain and other symptoms. About 10 percent of all kidney stones are uric acid stones. The good news is that they often dissolve with the right treatment.

Your body produces uric acid when it breaks down purines, compounds found in certain foods and naturally present in your cells. When uric acid builds up in acidic urine, it creates the perfect conditions for stone formation. Understanding your urine pH is key to preventing these stones from forming in the first place.

• Severe pain in your back, side, lower abdomen, or groin that comes in waves
• Blood in your urine, which may appear pink, red, or brown
• Frequent urge to urinate or urinating more often than usual
• Burning sensation or pain when you urinate
• Cloudy urine with a strong smell
• Nausea and vomiting, especially during pain episodes
• Fever and chills if an infection develops
• Inability to urinate or only passing small amounts of urine

Some people have small uric acid stones that pass without symptoms. You may never know you had a stone unless it shows up on imaging done for another reason. Larger stones cause more noticeable problems as they move through your urinary system.

The primary cause of uric acid kidney stones is persistently acidic urine with a pH below 5.5. When your urine is too acidic, uric acid cannot stay dissolved and begins to form crystals. Several factors make your urine more acidic, including diets high in animal protein, chronic diarrhea, type 2 diabetes, metabolic syndrome, and certain genetic conditions. Dehydration concentrates your urine and makes stone formation more likely. People who eat large amounts of red meat, organ meats, and seafood produce more uric acid.

Other risk factors include obesity, gout, family history of kidney stones, and certain medications. Men develop uric acid stones more often than women. Your risk increases as you age, particularly after age 40. Some people have metabolic issues that cause their bodies to produce excess uric acid or make their urine naturally more acidic. Medical conditions like inflammatory bowel disease can also increase risk by causing chronic diarrhea, which makes urine more acidic.

Doctors diagnose uric acid kidney stones using imaging tests and urine analysis. A CT scan or ultrasound can show stones in your kidneys or urinary tract. Urine pH testing is critical because persistently acidic urine below 5.5 indicates high risk for uric acid stone formation. Your doctor may collect a 24-hour urine sample to measure uric acid levels, urine volume, and pH patterns throughout the day.

Rite Aid offers urine pH testing through our preventive health panel at Quest Diagnostics locations. Monitoring your urine pH helps you understand your risk and track whether treatment is working. If you pass a stone, your doctor will analyze it to confirm it contains uric acid rather than calcium or other materials. Blood tests can check for conditions that increase stone risk, like gout or metabolic disorders.

• Drink 8 to 12 glasses of water daily to dilute urine and prevent stone formation
• Alkalinize your urine with potassium citrate or sodium bicarbonate to reach target pH of 6.0 to 6.5
• Reduce intake of red meat, organ meats, shellfish, and other high-purine foods
• Limit alcohol, especially beer, which increases uric acid production
• Maintain a healthy weight through balanced eating and regular physical activity
• Take allopurinol or febuxostat to lower uric acid production if dietary changes are not enough
• Eat more fruits and vegetables, which naturally make urine less acidic
• Monitor your urine pH regularly to ensure it stays in the target range
• Work with a doctor or dietitian to create a low-purine eating plan