Kidney stones and diarrhea might seem like unrelated health issues. But they’re actually connected in several important ways.
If you’re dealing with both conditions, you’re not alone. Many people experience diarrhea either as a cause of kidney stones or as a symptom alongside them. Understanding this connection can help you manage both conditions better and prevent future problems.
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What Are Kidney Stones?
Kidney stones are hard deposits that form inside your kidneys. They’re made up of minerals and salts that stick together. These stones can be as small as a grain of sand or as large as a golf ball.
When kidney stones move through your urinary tract, they can cause severe pain. Some people describe it as the worst pain they’ve ever felt. The stones can also cause other symptoms like blood in urine, nausea, and frequent urination.
Kidney Stones and Diarrhea
The relationship between kidney stones and diarrhea works in two main ways. Sometimes diarrhea can contribute to kidney stone formation. Other times, kidney stones or their treatments can cause diarrhea.
How Diarrhea Can Lead to Kidney Stones
Chronic diarrhea creates several conditions that increase your risk of developing kidney stones:
- Dehydration: Diarrhea causes you to lose fluids quickly. When you’re dehydrated, your urine becomes more concentrated. This makes it easier for minerals to crystallize and form stones.
- Electrolyte imbalances: Along with water, diarrhea causes you to lose important minerals like sodium, potassium, and magnesium. These imbalances can affect how your kidneys process minerals.
- Low citrate levels: Chronic diarrhea can reduce citrate levels in your urine. Citrate normally helps prevent kidney stones by stopping crystals from forming.
- Changes in urine pH: Diarrhea can make your urine more acidic. This acidic environment makes it easier for certain types of kidney stones to form.
Research shows that people with chronic diarrhea have a higher risk of developing kidney stones. A large study found that chronic diarrhea was associated with a 68% increased risk of kidney stones (1).
Research shows that people with chronic diarrhea face several health challenges. Bile acid malabsorption is a common but often overlooked cause of chronic diarrhea that can significantly impact quality of life (1). When chronic diarrhea occurs, the resulting dehydration and mineral imbalances can increase the risk of kidney stone formation.
How Kidney Stones Can Cause Diarrhea
Kidney stones themselves don’t directly cause diarrhea. But several related factors can lead to digestive issues:
- Pain and stress: The severe pain from kidney stones can trigger stress responses in your body. This stress can affect your digestive system and cause diarrhea.
- Medications: Some pain medications used for kidney stones can upset your stomach and cause diarrhea as a side effect.
- Nerve connections: Your kidneys and intestines share some nerve pathways. Irritation from kidney stones might affect these shared nerves and trigger digestive symptoms.
- Underlying conditions: Some health conditions can cause both kidney stones and digestive problems at the same time.
Medical Conditions That Link Kidney Stones and Diarrhea
Several medical conditions can cause both kidney stones and chronic diarrhea. Understanding these connections helps explain why some people experience both problems together.
Inflammatory Bowel Disease
People with Crohn’s disease or ulcerative colitis often develop both diarrhea and kidney stones. The chronic inflammation in the intestines affects how the body absorbs nutrients and processes minerals. This creates perfect conditions for stone formation.
Bile Acid Malabsorption
Bile acid malabsorption (BAM) is a common but often overlooked cause of chronic diarrhea. Research shows that BAM affects a significant portion of people diagnosed with diarrhea-predominant irritable bowel syndrome (2). When bile acids aren’t properly absorbed, they can cause diarrhea and affect mineral absorption, potentially leading to kidney stones.
Celiac Disease
This autoimmune condition damages the small intestine when you eat gluten. The damage leads to poor absorption of nutrients and chronic diarrhea. People with celiac disease have an increased risk of developing kidney stones due to malabsorption issues.
Short Bowel Syndrome
People who have had parts of their small intestine removed may develop short bowel syndrome. This condition causes severe diarrhea and malabsorption. The combination of fluid loss and mineral imbalances significantly increases kidney stone risk.
Treatment Considerations When Both Conditions Occur
Managing kidney stones and diarrhea together requires careful attention to avoid making either condition worse. Here’s what you need to know about treatment approaches.
Fluid Management
Staying hydrated is crucial for both conditions, but the approach differs:
- For kidney stones: You need to drink plenty of water to help flush out stones and prevent new ones from forming.
- For diarrhea: You need to replace lost fluids and electrolytes, not just water.
Oral rehydration solutions can help with both conditions. Studies show that properly formulated rehydration solutions effectively treat dehydration from diarrhea (3). These same fluids can also help maintain the hydration needed to prevent kidney stone formation.
Medication Adjustments
Some medications can affect both conditions:
- Pain medications: NSAIDs for kidney stone pain might worsen diarrhea in some people. Your doctor may recommend alternatives.
- Antidiarrheal drugs: Some medications that stop diarrhea can affect mineral absorption and potentially influence stone formation.
- Bile acid sequestrants: For people with bile acid malabsorption, these medications can reduce diarrhea. Studies show that colesevelam effectively treats BAM-associated diarrhea in patients with inflammatory bowel conditions (4).
Dietary Modifications
Diet plays a crucial role in managing both conditions:
- Limit oxalate-rich foods: If you have calcium oxalate stones, reducing foods high in oxalates can help. But don’t eliminate calcium, as it actually helps prevent stones when eaten with oxalate foods.
- Reduce sodium: High salt intake increases calcium in urine and can worsen both kidney stones and diarrhea.
- Consider FODMAPs: Research shows that dietary triggers like fructose can cause abdominal symptoms in people with irritable bowel syndrome (5). Avoiding these foods might help reduce diarrhea.
- Increase citrate: Citrus fruits and their juices contain citrate, which helps prevent kidney stones. But introduce them slowly if you have sensitive digestion.
Prevention Strategies for Both Conditions
Taking steps to prevent both kidney stones and diarrhea requires a balanced approach. Here are evidence-based strategies that can help with both conditions.
Hydration Guidelines
Proper hydration prevents kidney stones and helps manage diarrhea:
- Drink throughout the day: Aim for pale yellow urine as a sign of good hydration.
- Include electrolytes: When you have diarrhea, plain water isn’t enough. Add electrolyte solutions to maintain mineral balance.
- Monitor your intake: Research on oral rehydration therapy shows that careful fluid monitoring improves outcomes in dehydration management (6).
Dietary Balance
A balanced diet helps prevent both conditions:
- Adequate fiber: Soluble fiber can help with diarrhea, while the right amount of fiber supports overall digestive health.
- Calcium intake: Get enough calcium from food sources. It binds with oxalates in your intestines, preventing absorption and stone formation.
- Limit problem foods: Identify and avoid foods that trigger your diarrhea while also managing stone-forming foods.
Medical Monitoring
Regular check-ups help catch problems early:
- Urine tests: These can show if you’re at risk for kidney stones before they form.
- Stool tests: These can identify causes of chronic diarrhea like infections or malabsorption.
- Blood work: This monitors electrolyte levels and kidney function.
Special Populations at Higher Risk
Some groups face higher risks of developing both kidney stones and diarrhea-related complications.
Cancer Patients
Cancer treatments often cause severe diarrhea. Studies show that medications like tyrosine kinase inhibitors frequently cause diarrhea in patients with kidney cancer (7). The combination of dehydration from diarrhea and kidney stress from treatments increases stone risk.
People with Diabetes
Diabetes can affect both kidney function and digestive health. Diabetic patients may experience:
- Increased risk of kidney stones due to metabolic changes
- Diabetic diarrhea from nerve damage
- Medication side effects affecting both systems
Post-Surgical Patients
People who have had intestinal surgery face unique challenges. Research on intractable diarrhea shows that patients with severe malabsorption require specialized nutritional support (8). These patients need careful monitoring for both diarrhea and kidney stone development.
When to Seek Medical Help
Knowing when to get medical attention is crucial for both conditions. Don’t wait if you experience these warning signs.
Emergency Symptoms
Seek immediate medical care if you have:
- Severe abdominal or back pain that doesn’t improve with pain medication
- Blood in your urine along with diarrhea
- Signs of severe dehydration (dizziness, rapid heartbeat, decreased urination)
- Fever above 101°F with either condition
- Inability to keep fluids down due to vomiting
Non-Emergency Medical Consultation
Schedule an appointment if you have:
- Diarrhea lasting more than a week
- Recurring kidney stone symptoms
- Unexplained weight loss with chronic diarrhea
- Changes in your usual bowel patterns
The Bottom Line
Kidney stones and diarrhea share important connections that affect millions of people. Chronic diarrhea can increase your risk of developing kidney stones through dehydration, mineral loss, and metabolic changes. At the same time, kidney stones and their treatments can sometimes trigger digestive symptoms including diarrhea.
The key to managing both conditions lies in understanding their relationship and taking a comprehensive approach to treatment. Stay well-hydrated, work closely with your healthcare team, and don’t ignore persistent symptoms. With proper management, you can reduce your risk of kidney stones while effectively controlling diarrhea, improving your overall quality of life.