Your kidneys are fist-sized organs on either side of your spine. Each day they create one to two quarts of urine. It moves from the kidneys through tube-shaped ureters into your bladder, which is located in each kidney.

Kidney stones can cause intense pain in the lower back and abdomen known as renal colic. It is important to seek medical attention if you have these symptoms.

Symptoms

A kidney stone is a small rock that forms in your kidney. It may cause pain or other symptoms if it moves into the ureters, which are the tubes that carry urine from one kidney to your bladder. This causes a blockage, which results in severe pain. You may also feel pressure or a burning sensation when you urinate, and the pain may come in waves. The pain may start in your side, belly or groin and travel to your lower back.

Most stones are less than three-sixteenths of an inch (five mm) in size, so they pass on their own. Larger ones are more likely to get stuck in the ureters or the bladder and require medical treatment.

Your healthcare provider will examine you, and a blood test may show the levels of chemicals in your urine that can help identify the type of kidney stone you have. You’ll have imaging tests like a CT scan or ultrasound to see the shape, location and number of your stones.

Your healthcare provider will recommend that you drink lots of fluids to help your kidney stone pass or dissolve. They might also give you an over-the-counter pain medicine or, in the hospital, a narcotic to ease the pain. Some people need to have their ureters stretched out with a stent to make it easier for the kidney stones to pass.

Diagnosis

When a kidney stone blocks the ureter, it can cause a backup of pee that can make one or both of your kidneys swell and cause severe pain in your side and back. Other symptoms may include blood in your urine, fever, chills, vomiting or abdominal pain. Your doctor can diagnose kidney stones based on your symptoms and the results of a physical exam. You may also have a urinalysis and other lab tests, like blood work and tests that look for crystals in your urine. Imaging tests, such as an abdominal x-ray or a CT scan, can show the size and location of a kidney stone.

Kidney stones are most often caused by too much calcium, uric acid or oxalate in your urine or by a condition that makes it hard for the fluid in your urine to dilute these substances. Kidney stones can also form from cystine, an amino acid found in some foods, if you have the rare, inherited metabolic disorder called cystinuria.

UTIs can be diagnosed by a urine test, but it's important to distinguish between them and kidney stones. UTIs are typically felt as a sharp pain in the belly or lower abdomen and groin, and the pain can change intensity or go away completely. Kidney stone pain is usually a constant pressure in the side and back, and it can also become intense and spread to your belly and groin.

Treatment

When a kidney stone is diagnosed, your healthcare provider will first decide whether you need treatment. Some smaller stones may pass on their own if the pain is tolerable, the stone is not blocking the flow of urine and you are drinking enough water. Over-the-counter pain relievers like ibuprofen or acetaminophen may be helpful. You may also take medicines that help the kidney stones pass or reduce the size of the stone. Commonly prescribed medicines include calcium channel blockers (like tamsulosin and Flomax) or alpha-blockers that relax the ureter -- the tube through which pee passes from your kidney to your bladder -- and make it wider, making it easier for kidney stones to pass. You can also take potassium citrate or sodium citrate, which keep stones formed from uric acid or calcium oxalate from forming.

Kidney stones that are very large or causing severe symptoms require different treatment. Your doctor will collect a sample of the stone and test it for its type and chemical composition. They will also collect urine to see if you have a condition called cystinuria, which can cause stones made from the protein cystine.

The most commonly used treatments for larger stones are shock wave lithotripsy and ureteroscopy with laser lithotripsy. These are endoscopic procedures that involve looking at the urethra or bladder and removing the stones using a device inserted into your body through a small, flexible tube.

Prevention

The best way to prevent kidney stones is to drink plenty of fluids -- especially water. This dilutes the waste products that can cause stones, and it may help them pass more easily. If you have one stone, you're at risk for having another within 10 years, but drinking about 3 liters of fluid per day (ten standard 8-ounce glasses) and following other preventive tips can reduce your chances of having more.

Kidney stones often pass without causing pain or long-term problems, but they can also block the flow of urine, which may cause an infection or other symptoms. Treatment depends on the size of the stone, where it is in the kidney, and how bad the symptoms are.

Some stones can be broken up or removed with medicine. Then doctors can try to keep the stone from forming again. Drinking extra water, avoiding high-salt foods and taking certain medicines can help. Some types of stones require more specific treatments, like a drug called pyridoxine citrate, which helps make the urine less acidic and lowers the chance that the stone will form from cystine, an amino acid found in some foods.

Surgery is used to remove larger stones or if the stones are causing blockage. In some cases, a doctor can insert a tube (ureteral stent) to allow the flow of urine through an inflamed ureter.