Uric Acid Stones

What are uric acid stones?

Uric acid stones are one of four types of kidney stones. A kidney stone is a collection of minerals and salt that hardens. Kidney stones form in your kidneys or urinary system — the path that urine (pee) takes to leave your body.

Uric acid stones cause pain while peeing and blood in your pee (hematuria). These symptoms can be alarming. But there’s no reason to feel embarrassment, even though they affect a sensitive area of your body. Visit a healthcare provider as soon as possible to get an official diagnosis and so they can make sure there aren’t any other complications.

What is uric acid?

Uric acid is a waste product in your blood. Your body produces uric acid when it breaks down purines. Purines are substances that are common in meats and certain types of alcohol, including beer and liquor.

Most uric acid dissolves in your blood and passes through your kidneys. It leaves your body in your pee. But uric acid stones form when:

• Levels of uric acid in your pee are too high.
• Your pee is regularly too acidic.

How common are uric acid stones?

Researchers estimate that about 1 in 10 people in the United States will have a kidney stone at some point in their lives. Uric acid stones account for between 8% and 10% of all kidney stones.

What are the symptoms of uric acid stones?

Uric acid stones have similar symptoms to other types of kidney stones. The main symptom is pain from irritation or blockages inside your kidneys or urinary system. You may feel pain in your:

• Lower back.
• Sides (flanks).
• Abdomen.
• Groin.

Other symptoms include:

• Blood in your pee.
• Nausea or vomiting.
• Fever.
• Chills.
• Foul-smelling urine.
• Cloudy urine.

How do uric acid stones form?

If you have high levels of uric acid in your body (hyperuricemia), uric acid crystals start to form. These uric acid crystals combine with other substances in your body and create a solid stone. The mass keeps growing. It may stay in your kidney or move down your urinary system and settle in your ureter (ureteral stone).

If the stones are very small, they may pass out of your body in your pee with little or no pain. But if they don’t pass, they cause pee to back up in your kidney, ureter, bladder or urethra. That’s when you get pain and other symptoms because the stones damage the walls of whatever tube they’re in.

What is the most common cause of uric acid stones?

The most common causes of high acidity in your pee are:

Trouble processing uric acid or protein in your diet

When your body has trouble processing uric acid or protein, acid builds up in your pee. You usually inherit these issues from your biological parents.

A related condition is gout. Gout causes high uric acid levels in your blood and painful crystal deposits in your joints.

Foods high in purines

Animal proteins, including beef, poultry, pork, eggs and fish, contain high levels of purines. Organ meats, such as liver and kidneys, have the highest levels.

If you eat a lot of animal proteins, uric acid may build up in your pee. It can settle and form a stone, either by itself or with calcium.

Usually, your eating patterns alone won’t cause uric acid stones. They often occur in people who eat a lot of purines and are prone to developing them.

Other causes of high uric acid levels

Other causes of high uric acid levels include:

• A body mass index (BMI) greater than 25 (have overweight/obesity).
• Certain medications and supplements, including diuretics and immunosuppressants.
• Chemotherapy.
• Type 2 diabetes.
• Eating a lot of salt and sugar.
• Having a biological family history of kidney stones.
• Not getting enough physical activity.
• Having weight loss surgery (bariatric surgery).

You have a higher chance of developing uric acid stones and other types of kidney stones if you don’t drink enough water.

Who do uric acid stones affect?

Men and people assigned male at birth (AMAB) are more likely to have any type of kidney stone. For men and people AMAB, the lifetime risk is about 19%. For women and people assigned female at birth (AFAB), it’s about 9%.

Most people don’t get kidney stones before 30. But it’s possible to have them earlier in life, even among children.

What are the complications of uric acid stones?

Any type of kidney stone increases your risk of developing chronic kidney disease (CKD). If you have a stone, you’re at a higher risk of getting another one in the next five to seven years.

How are uric acid stones diagnosed?

A healthcare provider will review your medical history, ask about your symptoms and perform a physical exam. If they suspect you have a uric acid stone, they’ll order diagnostic testing.

What tests will be done to diagnose uric acid stones?

A healthcare provider may order the following tests to diagnose uric acid stones:

• Blood tests. Blood tests can detect too much uric acid or calcium in your blood. They can also suggest or rule out other conditions that may be causing your symptoms.
• Pee test (urinalysis). A provider may ask you to do a 24-hour urinalysis. You collect your pee over 24 hours, and then, your provider will test it for uric acid and calcium.
• Imaging tests. A CT scan or ultrasound can locate uric acid stones in your urinary system. Imaging tests can even find small stones. Providers usually don’t use abdominal X-rays because they may miss smaller stones.
• Stone analysis. You may need to pee into a special strainer to catch any stones that you pee out (pass). The provider will send the stone to a lab for analysis to figure out what type of stone it is. Analyzing the stone helps your provider determine the cause and how you can prevent stones from developing again.

How do you get rid of uric acid stones?

Small stones (less than 7 millimeters in diameter) may pass on their own. It can take up to three weeks to pass. But even if a stone passes on its own, it’s still important to talk to a healthcare provider so you can prevent uric acid stones from forming again.

The most important step in treating uric acid stones is to drink plenty of water. Drinking lots of water:

• Reduces the concentration of minerals in your pee. Fluids dissolve minerals, allowing them to leave your body through your pee.
• Encourages you to pee often, which flushes away minerals that can form stones.

Providers recommend that you drink enough fluids to produce about 2.5 liters (2.6 quarts) of pee. To produce that much pee, you need to drink about 3 liters (3.1 quarts) of fluid per day. That’s because you lose fluid through sweating or exercise.

Although drinking any fluid is important, it’s best to drink water.

What medication dissolves uric acid stones?

Uric acid stones are the only type of kidney stone that medications may be able to dissolve. These include:

• Potassium citrate tablets (Urocit-K®).
• Calcium carbonate tablets (Tums®).
• Allopurinol.

Potassium citrate or calcium carbonate tablets make your pee’s pH levels more basic (alkali). Allopurinol lowers your uric acid levels. If your healthcare provider prescribes these medications to you, it’s important to drink a lot of water. Drinking more water makes it easier for uric acid to dissolve.

Your provider may also prescribe alpha-blockers, which can help stones in your ureter pass faster.

Will I need surgery for uric acid stones?

You may need surgery if your uric acid stone:

• Is very large.
• Blocks your urine flow.
• Causes an infection.
• Doesn’t pass after four to six weeks.

Surgical treatment options include minimally invasive or noninvasive techniques, including:

• Extracorporeal shock wave lithotripsy. This is a noninvasive procedure that uses high-energy sound waves to break up the stones. There isn’t a cut (incision), and nothing enters your body.
• Ureteroscopy. A provider inserts a long, thin tool (endoscope) through your urethra into your affected ureter. Then, the surgeon removes the stone using a tiny basket. In some cases, they can break the stone using a laser and then remove the pieces.
• Percutaneous nephrolithotomy (PCNL). Providers use PCNL for larger stones. A surgeon makes a small incision in your back to access your kidney. They’ll either remove the stone or break it up first and then remove it.

After the procedure, the provider will send the stone or stone pieces to a lab for analysis.

How does drinking water help reduce the risk of uric acid stones?

Drinking the daily recommended amount of water is one of the best things you can do to reduce the risk of uric acid stones and other kidney stones. Fluids help dilute the waste products in your pee and wash away chemicals so stones don’t form.

How else can I prevent uric acid stones?

Other steps you can take to help prevent uric acid stones include:

• Drinking at least between 91 ounces (2.7 liters) and 125 ounces (3.7 liters) of fluids every day, preferably water.
• Maintaining a healthy weight for you.
• Following the Dietary Approaches to Stop Hypertension (DASH) eating plan, which can reduce both high blood pressure (hypertension) and the risk of developing kidney stones.
• Taking any medications your provider prescribes to help prevent uric acid stones from forming.

What can I expect if I have uric acid stones?

The outlook for uric acid stones and other kidney stones is good. Many times, stones pass on their own. You may not even need treatment. If you do need treatment, the options have good success rates. You’ll likely make a full recovery.

But there’s a risk of uric acid stones coming back. Talk to your healthcare provider about changes to what you eat and other steps you can take to prevent uric acid stones from forming again.

How do I take care of myself?​

If you have a history of uric acid stones or you’re at an elevated risk of developing one (or any type of kidney stone), the following steps can help you stay healthy:

• Drink plenty of water.
• Follow a healthy diet.
• Take any medications or supplements as your provider prescribes.
• Reach out to your provider if you have severe pain or other concerning symptoms.

What foods should you avoid if you have uric acid stones?

Avoid or limit foods that are high in purines. Too much purine causes your body to produce more uric acid. High uric acid levels lead to more acid in your pee, which can cause uric acid stones to form.

Examples of high-purine foods include:

• Red meats.
• Organ meats.
• Beer and alcohol.
• Meat-based gravies.
• Sardines, anchovies and shellfish.

It also helps to limit sugary foods and drinks, especially those that have high-fructose corn syrup.

It’s a good idea to eat more:

• Fruits and vegetables.
• Whole grains.
• Low-fat dairy products.

When should I see a healthcare provider?

Call a healthcare provider or go to the emergency room (ER) if you think you have a uric acid stone and you have the following symptoms:

• A fever greater than 101.5 degrees Fahrenheit (38.6 degrees Celsius).
• A stinging or burning sensation when you pee.
• Intense pain.
• Blood in your pee.
• Nausea and vomiting that don’t go away.
• A condition that puts you at a higher risk of developing kidney stone complications, such as diabetes, having only one kidney or any kidney problems.

What questions should I ask a healthcare provider?

• What treatment will work best for me?
• Will I need surgery?
• How can I prevent a uric acid stone from forming again?
• Should I make any changes to what I eat?
• Do I need to take any supplements or medications?