Uric Acid Nephrolithiasis (Kidney Stones)

What is Uric Acid Nephrolithiasis (Kidney Stones)?

Uric acid nephrolithiasis is a type of kidney stone that forms when uric acid crystals build up in your kidneys. Uric acid is a waste product your body makes when it breaks down purines, which are natural substances found in many foods and in your own cells. When uric acid levels get too high or your urine becomes too acidic, these crystals can stick together and form hard stones.

These stones differ from the more common calcium kidney stones. Uric acid stones tend to form when urine pH drops below 5.5, making the environment more acidic. The good news is that uric acid stones can sometimes dissolve with the right treatment, unlike calcium stones which usually need to be passed or removed.

About 5 to 10 percent of all kidney stones are uric acid stones. They are more common in people with gout, diabetes, metabolic syndrome, or those who eat a lot of animal protein. Understanding your uric acid levels through blood testing helps you prevent these stones before they form.

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Symptoms

Severe pain in your side, back, or below your ribs that comes in waves
Pain that radiates to your lower abdomen and groin
Pain or burning sensation when you urinate
Pink, red, or brown urine indicating blood
Cloudy or foul-smelling urine
Nausea and vomiting
Frequent need to urinate
Urinating small amounts at a time
Fever and chills if infection is present

Some people have small stones that pass without symptoms. Others may have stones that grow silently until they cause a blockage or severe pain.

Causes and risk factors

Uric acid kidney stones form when your urine contains too much uric acid or becomes too acidic. High-protein diets, especially those rich in red meat, organ meats, and shellfish, increase uric acid production in your body. Chronic diarrhea, certain digestive conditions, and not drinking enough water can make your urine more concentrated and acidic. Genetic factors play a role too, as some people naturally produce more uric acid or have kidneys that struggle to remove it efficiently.

Medical conditions like gout, type 2 diabetes, metabolic syndrome, and obesity significantly raise your risk. Chemotherapy and radiation therapy can temporarily spike uric acid levels as cancer cells break down. Some medications, including certain diuretics and low-dose aspirin, can also increase uric acid levels. Living in hot climates or doing intense physical activity without proper hydration concentrates your urine and creates an environment where stones can form.

How it's diagnosed

Doctors diagnose uric acid kidney stones through a combination of imaging tests and lab work. CT scans or ultrasounds can detect stones in your kidneys or urinary tract. Blood tests measure your serum uric acid levels to assess your risk and guide treatment decisions. Urine tests collected over 24 hours show how much uric acid your body produces and excretes, as well as your urine pH level.

Rite Aid offers serum uric acid testing as part of our flagship health panel at Quest Diagnostics locations nationwide. Regular testing helps you monitor your uric acid levels and catch problems before stones form. If you pass a stone, your doctor may analyze it in a lab to confirm it is made of uric acid rather than calcium or other minerals.

Treatment options

Drink 2 to 3 liters of water daily to dilute urine and prevent crystal formation
Reduce intake of high-purine foods like red meat, organ meats, sardines, and shellfish
Limit alcohol, especially beer, which raises uric acid levels
Eat more fruits and vegetables to make urine less acidic
Maintain a healthy weight through balanced nutrition and regular activity
Take potassium citrate or sodium bicarbonate to make urine more alkaline and dissolve stones
Use allopurinol or febuxostat medications to lower uric acid production
Manage underlying conditions like diabetes, gout, and metabolic syndrome
Work with a doctor for pain management during stone passage
Consider lithotripsy or surgical removal for large stones that do not dissolve

Frequently asked questions

Uric acid stones form when uric acid crystals accumulate in acidic urine. Unlike calcium stones, uric acid stones can sometimes dissolve with medications that make your urine more alkaline. They also do not show up on regular X-rays, so doctors use CT scans or ultrasounds to find them.

Yes, you can develop uric acid kidney stones without having gout. High uric acid levels, acidic urine, dehydration, and certain diets increase your risk. Many people with uric acid stones have never experienced a gout attack but still produce too much uric acid or have very acidic urine.

If you have had uric acid kidney stones, testing every 3 to 6 months helps monitor your levels. Once your uric acid is stable and controlled, you can test annually. Regular monitoring lets you adjust your diet or medications before new stones form.

Limit red meat, organ meats, shellfish, sardines, and anchovies, which are high in purines. Reduce alcohol, especially beer, and limit sugary drinks with high-fructose corn syrup. Focus on plant-based proteins, low-fat dairy, and plenty of water to lower your risk.

Yes, drinking 2 to 3 liters of water daily is one of the most effective prevention strategies. Water dilutes uric acid in your urine and helps maintain a healthy pH. If your urine is pale yellow or clear, you are likely drinking enough.

Normal serum uric acid levels are generally 3.5 to 7.2 milligrams per deciliter for men and 2.6 to 6.0 for women. Levels above 7.0 increase your risk of kidney stones and gout. Your doctor may recommend treatment if your levels are consistently elevated, especially if you have a history of stones.

No, small uric acid stones can pass through your urinary tract without causing symptoms. Some people only discover they have stones during imaging tests for other reasons. However, larger stones or those that block urine flow typically cause severe pain.

Yes, medications like potassium citrate or sodium bicarbonate can make your urine more alkaline and dissolve existing uric acid stones over time. Allopurinol and febuxostat lower uric acid production to prevent new stones. This treatment approach works specifically for uric acid stones, not calcium stones.

Genetic factors can increase your risk of uric acid kidney stones. Some people inherit tendencies to produce more uric acid or have kidneys that make more acidic urine. If family members have had kidney stones or gout, your risk may be higher.

Small stones, under 4 millimeters, usually pass within 1 to 2 weeks with plenty of fluids and pain management. Larger stones may take 2 to 3 weeks or require medical intervention. Stones larger than 6 millimeters often need lithotripsy or other procedures to break them up or remove them.