Urology
Kidney Stones
Kidney stones can be painful and increase your risk for infections. Our urology experts offer the latest minimally invasive treatments. We also help lower your risk of developing more kidney stones.
Medically reviewed by Marc Dall'Era, M.D. on Nov. 13, 2023.
Complete Care for Kidney Stones
Experts at the UC Davis Health Department of Urologic Surgery provide complete care for kidney stones. If you develop kidney stones, our endourologists specialize in minimally invasive procedures. We also offer treatments to prevent kidney stones from forming.
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What Are Kidney Stones?
Kidney stones are crystals of minerals and salt that form in urine in one or both kidneys. They’re also called renal stones. Renal is the medical term for kidneys.
Some kidney stones are the size of a grain of sand and don’t cause problems. These stones may stay in your kidney or painlessly leave your body when you urinate.
Larger stones can get stuck in your ureter, the tube that connects your kidney and bladder. These stones can block urine flow, causing urinary tract infections (UTIs), pain and other problems. Large kidney stones, as well as multiple small stones, often require treatment.
Types of kidney stones vary, depending on the main mineral:
- Calcium stones account for 8 in 10 kidney stones. They contain either calcium oxalate or calcium phosphate.
- Struvite stones usually form after a UTI.
- Uric acid stones form from purine, a natural substance found in shellfish, fish and meats.
- Cystine stones affect people who have a rare genetic condition called cystinuria. A natural chemical called cystine leaks into your urine and forms kidney stones.
Kidney Stone Symptoms
Small kidney stones don’t always cause symptoms. You might not know you have a kidney stone until it gets bigger or moves into your ureter, causing a blockage.
Common Symptoms
Signs of kidney stones include:
- Blood in your urine
- Burning sensation during urination
- Dull lower back pain that comes and goes, or sharp pain that moves to your abdomen or groin
- Fever and chills
- Frequent urination or intense need to urinate
- Foul-smelling or cloudy urine
- Nausea and vomiting
Emergency Symptoms
In rare instances, an untreated UTI from a kidney stone blockage can lead to sepsis. Sepsis is a life-threatening medical emergency. Seek immediate care if you experience:
- Confusion
- Difficulty breathing
- Extremely high or low body temperature
- Fast heart rate or low blood pressure
- Rash of dark red spots
- Shakiness
Causes of Kidney Stones
Kidney stones form from higher-than-usual amounts of minerals and salt in your urine. Several factors can lead to kidney stones.
Dehydration and Low Urine Volume
When you don’t drink enough fluids, your body can’t make enough urine to dissolve salts and flush minerals from your kidneys.
High-Salt Diet
Too much salt (sodium) in your diet can interfere with calcium absorption, leading to calcium stones. The amount of calcium you have in your diet doesn’t cause calcium stones.
Risk Factors for Kidney Stones
Anyone can develop kidney stones. These factors increase your risk.
Biological Sex
Males are almost twice as likely to develop kidney stones as females.
Excess Weight
Excess weight or obesity can change acid levels in your urine, causing stones to form.
Family History
Kidney stones often run in families. Your risk is higher if a parent or sibling has had kidney stones.
Health Conditions
Certain kidney diseases, thyroid disorders and digestive disorders can increase your risk.
Medication and Treatment Side Effects
Diuretics, antacids and medications for seizures (epilepsy) and HIV can cause stones to form. You’re also more at risk if you’ve had gastrointestinal surgery.
Diagnosis and Testing of Kidney Stones
Our providers quickly diagnose kidney stones using these tests:
- Blood test to check for high mineral levels and bacteria that may indicate a urinary tract infection (UTI).
- Urine test (urinalysis) to look for blood, minerals and bacteria in your urine.
- Medical imaging tests, such as X-rays or a CT scan to determine the size, number and location of kidney stones.
Kidney Stone Treatments
Treatment depends on the kidney stone size, type, amount and location. When appropriate, our endourologists use minimally invasive procedures to treat kidney stones. They use tiny cameras and flexible tubes (scopes) to guide the procedure.
Medications and Fluids
For small stones, your provider may recommend pain medication and drinking more fluids to help pass the stone. You may use a special container to catch the stone. A lab examines it to determine the mineral type.
Shock Wave Lithotripsy
Your provider sends a series of high-energy shock waves through your skin. The shock waves break large stones into smaller pieces, which are easier to pass when you urinate.
Ureteroscopy
Your provider inserts a long, thin scope through your urethra (the tube that carries urine out of your body) and into your bladder and ureter. They remove the stone or use a laser to break it into smaller pieces. You receive anesthesia and are asleep during the procedure.
Percutaneous Nephrolithotomy
Your provider makes a small incision in your back to insert a scope directly into your kidney. They may remove kidney stones or use a laser to break them into smaller pieces. This procedure takes place while you’re under anesthesia.
Preventing Kidney Stones
Knowing the type of kidney stones you get can help you make changes to prevent future ones. But these steps may also help.
Stay Hydrated
Drinking plenty of nonalcoholic fluids is one of the best ways to help your kidneys flush out the minerals that form stones. Most experts recommend drinking six to eight 8-ounce glasses of fluids a day unless you have kidney disease.
Take Preventive Medications
Antibiotics can prevent struvite stones. Your provider may recommend taking potassium citrate to prevent calcium and uric acid stones.
Watch What You Eat
Depending on the type of kidney stone, you may need to cut back on sodium, shellfish and certain meats. You may also need to eat less nuts, spinach and other foods that contain a compound called oxalate. Your provider can recommend specific diet advice for you.
"What are kidney stones?" Urology Care Foundation, https://www.urologyhealth.org/urology-a-z/k/kidney-stones
"Definition & Facts for Kidney Stones," National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), https://www.niddk.nih.gov/health-information/urologic-diseases/kidney-stones/definition-facts
"Eating, Diet & Nutrition for Kidney Stones," NIDDKD, https://www.niddk.nih.gov/health-information/urologic-diseases/kidney-stones/eating-diet-nutrition
Conditions
Who does it affect?
1 in 10People will have a kidney stone during their lifetime
Annual hospital visits
500KPeople seek emergency care for kidney stones
Source: National Kidney Foundation: Kidney Stones
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