Understanding Uric Acid Stones: What Causes Them?

If you've been diagnosed with uric acid stones, it's important to understand why they form. Knowing the cause is the best way to prevent future stones and keep your urinary tract healthy. Uric acid stones are grouped into three categories: idiopathic, secondary, and congenital. Let's break each of these down.¹ ²

Idiopathic Uric Acid Stones: The Most Common Type

This is the most frequent category, and often, the exact reason for stone formation is tricky to pinpoint. However, we do know two main things play a big role:

• Acidic Urine (Low pH): Think of it like this: if your urine is too acidic, uric acid has a harder time staying dissolved and is more likely to clump together and form a stone. This can happen if your body produces too much acid or if it has trouble getting rid of acid properly.³ ⁴

  
  

• Insulin Resistance: This is often linked to things like obesity, metabolic syndrome, and type 2 diabetes. When your body is resistant to insulin, it can affect how your kidneys handle acid, making stones more likely.⁵ ⁶ ⁷

  
  

Secondary Uric Acid Stones: When Something Else is at Play

Sometimes, uric acid stones form because of another health issue or something you're doing. Here are some common culprits:

• High Purine Diet: Purines are found in certain foods, and when your body breaks them down, it makes uric acid. If you eat a lot of high-purine foods (like red meat and organ meats), you might have too much uric acid in your urine.

  
  

• Gout: Gout is a type of arthritis that causes high levels of uric acid in your body. This can lead to both joint pain and uric acid stones.

  
  

• Fluid and Alkali Loss: If you lose a lot of fluids and important substances called alkali (like malate and citrate) from your digestive system, your urine can become more concentrated and acidic, making stones more likely. This can happen with chronic diarrhea from conditions like irritable bowel syndrome (IBS) or if you've had certain types of surgery.⁸ ⁹ ¹⁰ Fat malabsorption can also play a role here.¹¹

  
  

• High Cell Turnover: This means your body is breaking down cells at a fast rate. When cells break down, they release substances that turn into uric acid. This can happen with certain cancers, during chemotherapy, or with some blood disorders.

  
  

• Certain Medications: Some medications can increase uric acid levels. It's important to know that you should never stop taking a medication without talking to a doctor first.¹²

  
  

Congenital Uric Acid Stones: Inherited Predisposition

In rare cases, people inherit genes that make them more prone to uric acid stones. These are called congenital conditions.¹²

What Can You Do?

The good news is that understanding the cause of your uric acid stones is the first step towards effective treatment and prevention.

Since most people with uric acid stones fall into the idiopathic category, treatment often focuses on making the urine less acidic and addressing insulin resistance.

Here are some things your doctor or dietitian might recommend:

• Dietary Changes: This could include losing weight, making healthier food choices (like eating more fruits and vegetables and less meat), and limiting alcohol.¹³ ¹⁴

  
  

Remember, it's crucial to work closely with your healthcare team to figure out the best approach for your specific situation. They can help you understand your risks and create a plan to keep your urinary tract healthy.

Florida Residents:

Looking for personalized kidney stone prevention? The Kidney Stone Prevention Clinic of Florida provides virtual consultations with nephrologist Dr. Paul Dreyer and dietitian Kidney Kat. We'll work with you, wherever you are in Florida. Follow the link to schedule your free 15-minute discovery call with the Kidney Stone Prevention Clinic of Florida today!

KIDNEY STONE CLINIC

References:

1.   Ma Q, Fang L, Su R, Ma L, Xie G, Cheng Y. Uric acid stones, clinical manifestations and therapeutic considerations. Postgrad Med J. 2018 Aug;94(1114):458-462. 

2.   Shen X, Pan Q, Huang Y, You J, Chen Y, Ding X. Metabolic Syndrome Predicts Uric Acid Stones in the Upper Urinary Tract: Development and Validation of a Nomogram Model. Arch Esp Urol. 2023 Jun;76(4):255-263. 

3.   Tran TVM, Maalouf NM. Uric acid stone disease: lessons from recent human physiologic studies. Curr Opin Nephrol Hypertens. 2020 Jul;29(4):407-413.

4.   Maalouf NM, Cameron MA, Moe OW, et al. Novel insights into the pathogenesis of uric acid nephrolithiasis. Curr Opin Nephrol Hypertens 2004; 13: 181.

5.   Abate N, Chandalia M, Cabo-Chan AV Jr, Moe OW, Sakhaee K. The metabolic syndrome and uric acid nephrolithiasis: novel features of renal manifestation of insulin resistance. Kidney Int. 2004;65(2):386–92. 

6.   Maalouf NM, Cameron MA, Moe OW, Sakhaee K. Metabolic basis for low urine pH in type 2 diabetes. Clin J Am Soc Nephrol. 2010 Jul;5(7):1277–81.

7.   Cameron MA, Maalouf NM, Adams-Huet B, Moe OW, Sakhaee K. Urine composition in type 2 diabetes: predisposition to uric acid nephrolithiasis. J Am Soc Nephrol. 2006 May;17(5):1422–8.

8.   Sakhaee K, Williams RH, Oh MS, Padalino P, Adams-Huet B, Whitson P, Pak CY. Alkali absorption and citrate excretion in calcium nephrolithiasis. J Bone Miner Res. 1993 Jul;8(7):789-94

9.   Rudman D, Dedonis JL, Fountain MT, et al. Hypocitraturia in patients with gastrointestinal malabsorption. N Engl J Med. 1980;303:657–661.

10.  Usui Y, Matsuzaki S, Matsushita K, Shima M. Urinary citrate in kidney stone disease. Tokai J Exp Clin Med. 2003;28:65–70.

11.  Moe OW, Xu LHR. Hyperuricosuric calcium urolithiasis. J Nephrol. 2018 Apr;31(2):189-196. 

12.  Manish KC, Leslie SW. Uric acid nephrolithiasis. 2023 Oct 15. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan

13.  Wiederkehr MR, Moe OW. Uric Acid Nephrolithiasis: A Systemic Metabolic Disorder. Clin Rev Bone Miner Metab. 2011 Dec;9(3-4):207-217.

14.   Pearle MS, Goldfarb DS, Assimos DG, et al. Medical management of kidney stones: AUA Guideline. J Urology. 2014; 192;316-324.

Important Disclaimers:

This article is general advice for those with kidney stones.  Not sure if you have kidney stone or low urine citrate?  Ask your doctor or dietitian about it.  Avoid any urge to self-diagnose. 

As with any dietary advice, this information is appropriate for most people, but not for everyone.  Yes, there are exceptions to every rule!  If your situation is complicated or unique, ask your medical provider for a referral to see a registered dietitian. 

Content on this site is for reference purposes and is not intended to substitute for advice given by your personal physician, pharmacist, dietitian or medical team. Please, do not use this information to self-diagnose or to treat a health problem or disease on your own. Contact your physician immediately if you suspect that you have a medical problem.