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Overview
What Are Kidney Stones?
Kidney stones are hard deposits made of minerals and salts that form inside the kidneys. A stone may stay in the kidney or move through the urinary tract, including the ureter and bladder. Some stones cause no symptoms, while others can cause severe pain or urinary problems as they move. Kidney stones can affect people of any sex or age.
Symptoms
Kidney Stone Symptoms
Small stones may cause no symptoms while they remain in the kidney. Symptoms often begin when a stone moves into the ureter and irritates or blocks the urinary tract. Common kidney stone symptoms include:
- Sharp or cramping pain in the side or back is a common symptom.
- Pain may move from the side or back toward the lower abdomen or groin.
- Pain or burning with urination can occur as the stone travels through the urinary tract.
- A frequent or urgent need to urinate may be a sign of a moving stone.
- Blood in the urine (hematuria) may make the urine pink, red, or brown.
- Cloudy or foul-smelling urine may occur, especially when infection is present.
- Nausea can occur along with severe kidney stone pain.
- Vomiting may occur when pain is intense or the urinary tract is irritated.
- Fever or chills may indicate an infection and require prompt medical assessment.
Get medical advice
Know when symptoms may be urgent
Severe pain, fever or chills, vomiting that prevents you from keeping fluids down, or difficulty urinating can signal a complication. Seek prompt medical assessment rather than waiting for symptoms to improve.
Causes
What Causes Kidney Stones?
Kidney stones form when urine contains more stone-forming substances than it can keep dissolved. Minerals and salts can then form crystals that grow and join together into a stone. Dehydration and some medical or inherited conditions can make this process more likely.
STONE TYPES
Calcium stones are the most common type and may involve calcium combined with oxalate or phosphate. Uric acid stones can form when urine is too acidic. Struvite stones are linked to certain urinary infections, while cystine stones result from an inherited disorder that causes cystine to enter the urine.
URINARY TRACT TERMS
Kidney stones form in the kidneys, while bladder stones form in the bladder and may have different causes. Both are stones in the urinary tract, but a kidney stone can move downward into the ureter or bladder.
Risk Factors
Kidney Stone Risk Factors
| Risk factor type | Examples |
|---|---|
| Nonmodifiable or inherited | Family history, previous stones, and inherited conditions such as cystinuria |
| Modifiable or treatable | Low fluid intake, high sodium or animal-protein intake, obesity, certain digestive or metabolic conditions, recurrent urinary infections, and some medicines |
Having a risk factor does not guarantee that you will develop a kidney stone. After a stone episode, a clinician can review your health history, diet, medicines, and testing to identify personal risks and guide prevention.
Complications
Kidney Stone Complications
- Urinary obstruction can block the flow of urine through the ureter.
- Hydronephrosis is swelling of the kidney caused by backed-up urine.
- A urinary tract infection can develop when urine flow is blocked or bacteria are present.
- A kidney infection can occur if a urinary infection spreads upward.
- Ongoing obstruction or repeated infections may reduce kidney function.
- People who have had one kidney stone may develop recurrent kidney stones.
Important
Infection and blockage need urgent attention
An obstructed urinary tract with an infection can become dangerous. Fever, chills, severe weakness, or reduced urine with suspected kidney stones requires urgent medical care.
Diagnosis
How Kidney Stones Are Diagnosed
Clinicians review pain and urinary symptoms and examine you for signs of illness. They may ask about previous stones, medical conditions, medicines, diet, and family history. This information helps determine whether a stone, infection, obstruction, or another condition may be causing the symptoms.
LABORATORY TESTS
Urinalysis can look for blood, crystals, and signs of infection, while a urine culture may be used when infection is suspected. Blood tests can assess kidney function and related chemical levels. If a stone is passed, analysis may identify its type and help guide prevention.
IMAGING
Ultrasound, CT, or another imaging test can show a stone’s size, location, and effect on urine flow. The choice depends on symptoms, age, pregnancy status, and clinical need.
Treatment & Management
Kidney Stones Treatment and Management
Kidney stones treatment depends on the stone’s size, location, and composition, as well as your symptoms, overall health, and whether infection or blockage is present. A clinician will recommend the safest approach for the specific stone.
| Approach | When it may be used |
|---|---|
| Observation and medicines | For selected small stones that may pass safely, with clinician-directed pain control, fluids when appropriate, nausea treatment, and follow-up |
| Medical expulsive therapy | Medicines may help some stones pass through the ureter when prescribed and monitored by a clinician |
| Shock wave lithotripsy | Uses focused shock waves to break a suitable stone into smaller pieces that can pass |
| Ureteroscopy | Uses a small scope to reach the stone, remove it, or break it into pieces |
| Percutaneous nephrolithotomy | May be used for larger or complex stones through a small opening in the back |
| Urgent treatment | An infected obstruction requires urgent medical treatment to relieve blockage and control the infection |
Prevention
How to Prevent Kidney Stones
- Drink enough fluid as advised by your healthcare professional.
- Reduce excess sodium in your diet.
- Follow individualized dietary guidance based on your stone type and health needs.
- Avoid extreme high-protein diets when they are not appropriate for you.
- Maintain a healthy weight through sustainable eating and activity habits.
- Manage medical conditions that may contribute to stone formation.
- Take prescribed preventive medicines as directed.
Outlook and Prognosis
Outlook and Prognosis for Kidney Stones
Many smaller stones pass without a procedure, while larger or complicated stones may need treatment. The time required and the amount of discomfort vary according to the stone’s size and location. Follow-up is important even after symptoms improve because another stone may form.
When Should You See a Doctor
When Should You See a Doctor for Kidney Stones?
Contact a clinician
Get medical advice promptly
Contact a clinician for severe or persistent kidney stone pain, blood in the urine, repeated vomiting, difficulty urinating, or symptoms that do not improve. These symptoms may need testing and treatment.
Seek urgent care
Recognize emergency warning signs
Seek emergency care for fever or chills with suspected kidney stone symptoms, severe weakness, confusion, inability to keep fluids down, or very little or no urine. These may indicate a serious infection or urinary obstruction.
Branches
2 topics
Kidney Stones
Nephrology
Kidney Stones
Urology
Symptoms
3 topics
Kidney Stones
Abdominal Pain
Kidney Stones
Backache
Kidney Stones
Blood In Urine
