Frequently Asked Questions about Kidney Stones
More than 10% of people in the United States will have a kidney stone in their lifetime. Kidney stones can cause significant pain and poor quality of life.
A urologist can treat kidney stones to relieve the pain. It’s important to see a doctor as soon as you think you may have kidney stones. The earlier kidney stones are diagnosed, the more options a doctor has to treat them without using an invasive surgical procedure.
What is a kidney stone?
A kidney stone is a collection of tiny crystals in the urine that fuse together to create a hard ball that looks like a stone.
Sometimes kidney stones are called calculi (or calculus for just one), nephrolithiasis, or urolithiasis.
Stones can be found in the kidney or in the ureter, which is the tube that connects the kidney to the bladder. A stone found in the kidney is called a renal calculus. A stone found in the ureter is called a ureteral calculus.
How do kidney stones form?
Most stones form just under the inner surface of the kidney. Small crystals in your urine fuse together, similar to the way salt crystals form from evaporating saltwater.
More crystals can bind over time until a stone is formed. The stone can then continue to grow bigger and ultimately become so heavy that it breaks off within the kidney. Once free to move around, it can either stay in the kidney or try to pass down the ureter.
How long does it take kidney stones to form?
This is different in each patient. Typically, it takes several months for even small stones to form, but for people who are more likely to form stones, stone formation can happen in a matter of weeks.
What does it feel like to have a kidney stone?
Everyone experiences kidney stones differently. Typically, kidney stones within the kidney do not cause pain.
If a stone falls onto the opening where the kidney meets the ureter or passes into the ureter, this can prevent urine from draining out of the kidney. This backing up of urine can lead to back pain just below your ribs. Sometimes the pain can be severe enough to cause nausea and vomiting.
As a stone moves, the blockage of urine may be relieved and symptoms may improve or go away. The pain may return if the stone begins to cause blockage of urine again. This changing of symptoms is called renal colic.
Blood in the urine may be a sign of kidney stones. Sometimes the blood isn’t visible to the naked eye and must be detected by a urine test.
If a stone is able to pass down the ureter and close to the bladder, the pain may move to the front of the abdomen, near the pelvis.
Stones very close to the bladder can cause pain that is felt in the genitals. A stone that reaches the bladder can cause burning with urination or changes in how often or how urgently you need to urinate.
How can I tell if I have a kidney stone?
Routine screening for kidney stones common but not recommended for all people.
Kidney stones can be detected using imaging such as X-rays, ultrasound, CT scan, or MRI. The best imaging currently available for kidney stone detection is a CT scan.
If you have crystals in your urine, that does not mean that you have a kidney stone. Crystals in the urine are common. If you have crystals in your urine along with other symptoms of kidney stones, you should see a doctor for an exam and imaging.
What are risk factors for kidney stone formation?
Risk factors include:
- Hypertension (high blood pressure)
- Inflammatory bowel condition (Crohn’s disease, ulcerative colitis)
- Chronic diarrhea
- Prior bowel surgery including colon resection, small intestine resection, and weight loss surgery
- Thyroid disease (hyperthyroidism)
- Parathyroid disease (hyperparathyroidism)
- Renal tubular acidosis
- Medullary sponge kidney
- Neurogenic bladder
- Recurrent urinary tract infections
- Eating disorders (anorexia, bulimia)
- Diuretics (triamterene)
- Anti-seizure medication (topiramate, zonisamide)
- Long-term steroid use
- Anticongestants (guafenasin, ephedrine)
- Protease inhibitors (indinavir)
Family history of stone disease
Genetic risk factors
- Primary hyperoxaluria
- Idiopathic hypercalciuria
- Dehydration or poor fluid intake
- Overuse of vitamins
- Overconsumption salt
- Overconsumption of animal protein (red meat, white meat, fish)
- Overconsumption or underconsumption of calcium
- Overconsumption or underconsumption of oxalate
- Underconsumption of citrate
How do I treat my kidney stones?
You have multiple options for treating kidney stones. You and your physician will decide which option is best for you based on the location, size, hardness, and composition of your stones.
Options for treatment include:
Instead of treating the stones, you and your doctor wait to see if they grow or pass. Small stones that do not cause discomfort may not require treatment. But if the stones grow larger or pass into the ureter and cause pain, they may require treatment later.
In some circumstances (such as uric acid stones), medication can be used to dissolve stones in the kidney, with no surgical procedure needed.
A surgeon may use one of these procedures to remove stones:
Shockwave lithotripsy is the most common type of treatment for kidney stones. Ultrasound shockwaves are passed through the patient’s back break the stone into small pieces that can then pass on their own.
Shockwave lithotripsy works best for smaller stones and stones that are softer.
It does not work well for stones that are in the lower part of the kidney, because those stones have to travel upward to reach the ureter and thus pass out of the kidney.
It works much better for stones in the top part of the kidney, because those pieces can pass down and out by themselves.
In a ureteroscopy, your surgeon passes a small telescope through the urethra and up into the ureter or kidney to reach the stone. Then, a laser is used to break up the stone into small pieces. If those pieces are not small enough to pass on their own, they can be removed with a small basket.
Ureteroscopy is less effective for large stones, which are much harder to remove through the ureter.
Percutaneous nephrostolithotomy is generally used for large kidney stones. The surgeon makes a small incision about 1 centimeter long in the patient’s back and passes a telescope directly into the kidney. The doctor then uses specialized instruments passed through the telescope to break up the stones and remove the pieces with suction.
How can kidney stones be prevented?
Stones can be prevented by changing the chemistry of your urine by changing your diet or by taking medication. Some general dietary recommendations for stone prevention include:
- Increase fluid intake to make 2.5 liters of urine per day
- Limit intake of salt or high salt-containing foods
- Limit intake of non-dairy animal proteins (meat)
- Increase fruit and vegetable intake
- Eat a normal amount of calcium (1,000 to 1,200 mg) per day
- Limit oxalate intake
What are important factors to consider when choosing where to get care for kidney stones?
You should think about your kidney stone care as a process that has two phases: stone removal and stone prevention.
For stone removal, there are multiple surgical approaches. You should choose a provider who offers all of the different types of treatment. That gives you options for choosing the best approach rather than choosing a one-size-fits-all approach. This also increases your chances of being stone-free after a single stone procedure.
Stone prevention is sometimes not emphasized in a patient’s treatment plan. Prevention can help you avoid painful stones and more treatments later. Stone prevention begins with urine testing to determine your risk for forming more stones. Choose a provider who will perform this testing and provide you with personalized recommendations or medications for stone prevention. This will give you the best chance to prevent new stones.