Kidney stones (renal lithiasis) are small, hard deposits that form inside your kidneys. The stones are made of mineral and acid salts. Kidney stones have many causes and can affect any part of your urinary tract — from your kidneys to your bladder. Often, stones form when the urine becomes concentrated, allowing minerals to crystallize and stick together.

Passing kidney stones can be quite painful, but the stones usually cause no permanent damage. Depending on your situation, you may need nothing more than to take pain medication and drink lots of water to pass a kidney stone. In other instances, surgery may be needed. Your doctor may recommend preventive treatment to reduce your risk of recurrent kidney stones if you’re at increased risk of developing them again.

Symptoms
A kidney stone may not cause symptoms until it moves around within your kidney or passes into your ureter — the tube connecting the kidney and bladder. At that point, these signs and symptoms may occur:
Severe pain in the side and back, below the ribs

Pain that spreads to the lower abdomen and groin

Pain that comes in waves and fluctuates in intensity

Pain on urination

Pink, red or brown urine

Cloudy or foul-smelling urine

Nausea and vomiting


Persistent urge to urinate

Urinating more often than usual

Pain so severe that you can’t sit still or find a comfortable position

Pain accompanied by nausea and vomiting

Pain accompanied by fever and chills

Causes
Kidney stones often have no definite, single cause, although several factors may increase your risk. Kidney stones form when your urine contains more crystal-forming substances — such as calcium, oxalate and uric acid — than the fluid in your urine can dilute. At the same time, your urine may lack substances that keep crystals from sticking together, creating an ideal environment for kidney stones to form.

Treatments and drugs
Treatment for kidney stones varies, depending on the type of stone and the cause.

Small stones with minimal symptoms
Most kidney stones won’t require invasive treatment. You may be able to pass a small stone by:

1. Drinking water. Drinking as much as 2 to 3 quarts (1.9 to 2.8 liters) a day may help flush out your urinary system. Unless your doctor tells you otherwise, drink enough fluid — mostly water — to produce clear or nearly clear urine.

2. Pain relievers. Passing a small stone can cause some discomfort. To relieve mild pain, your doctor may recommend pain relievers such as ibuprofen (Advil, Motrin, others), acetaminophen (Tylenol, others) or naproxen sodium (Aleve).

3. Medical therapy. Your doctor may give you a medication to help pass your kidney stone. This type of medication, known as an alpha blocker, relaxes the muscles in your ureter, helping you pass the kidney stone more quickly and with less pain.

Large stones and those that cause symptoms
Kidney stones that can’t be treated with conservative measures — either because they’re too large to pass on their own or because they cause bleeding, kidney damage or ongoing urinary tract infections — may require more invasive treatment. Procedures may include:

1. Using sound waves to break up stones.

2. Surgery to remove very large stones in the kidney

3. Using a scope to remove stones

4. Parathyroid gland surgery.