Kidney stones (renal lithiasis, nephrolithiasis) are small, hard mineral deposits that form inside your kidneys. The stones are made of mineral and acid salts.
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, you may experience these signs and symptoms:
- 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 need to urinate
- Urinating more often than usual
- Fever and chills if an infection is present
- Urinating small amounts of urine
Pain caused by a kidney stone may change — for instance, shifting to a different location or increasing in intensity — as the stone moves through your urinary tract.
When to see a doctor
Make an appointment with your doctor if you have any signs and symptoms that worry you.
Seek immediate medical attention if you experience:
- 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
- Blood in your urine
- Difficulty passing urine
Risk factors
Factors that increase your risk of developing kidney stones include:
- Family or personal history.
- Dehydration.
- Certain diets. Eating a diet that’s high in protein, sodium and sugar may increase your risk of some types of kidney stones. This is especially true with a high-sodium diet. Too much sodium in your diet increases the amount of calcium your kidneys must filter and significantly increases your risk of kidney stones.
- Being obese.
- Digestive diseases and surgery.
- Other medical conditions. Diseases and conditions that may increase your risk of kidney stones include renal tubular acidosis, cystinuria, hyperparathyroidism, certain medications and some urinary tract infections.
Tests and diagnosis
If your doctor suspects you have a kidney stone, you may have diagnostic tests and procedures, such as:
- Blood testing.
- Urine testing.
- Imaging tests may show kidney stones in your urinary tract. Options range from simple abdominal X-rays, which can miss small kidney stones, to high-speed or dual energy computerized tomography (CT) that may reveal even tiny stones.
Other imaging options include an ultrasound, a noninvasive test, and intravenous urography, which involves injecting dye into an arm vein and taking X-rays (intravenous pyelogram) or obtaining CT images (CT urogram) as the dye travels through your kidneys and bladder.
- Analysis of passed stones. You may be asked to urinate through a strainer to catch stones that you pass. Lab analysis will reveal the makeup of your kidney stones. Your doctor uses this information to determine what’s causing your kidney stones and to form a plan to prevent more kidney stones.
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:
- 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.
- Pain relievers. Passing a small stone can cause some discomfort. To relieve mild pain, your doctor may recommend pain relievers such as ibuprofen, acetaminophen or naproxen sodium
- 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 extensive treatment. Procedures may include:
- Using sound waves to break up stones.
- Surgery to remove very large stones in the kidney.
- Using a scope to remove stones.
- Parathyroid gland surgery.
Prevention
Prevention of kidney stones may include a combination of lifestyle changes and medications.
Lifestyle changes
You may reduce your risk of kidney stones if you:
- Drink water throughout the day. For people with a history of kidney stones, doctors usually recommend passing about 2.6 quarts (2.5 liters) of urine a day. Your doctor may ask that you measure your urine output to make sure that you’re drinking enough water.
If you live in a hot, dry climate or you exercise frequently, you may need to drink even more water to produce enough urine. If your urine is light and clear, you’re likely drinking enough water.
- Eat fewer oxalate-rich foods. If you tend to form calcium oxalate stones, your doctor may recommend restricting foods rich in oxalates. These include rhubarb, beets, okra, spinach, Swiss chard, sweet potatoes, nuts, tea, chocolate and soy products.
- Choose a diet low in salt and animal protein. Reduce the amount of salt you eat and choose nonanimal protein sources, such as legumes. Consider using a salt substitute.
- Continue eating calcium-rich foods, but use caution with calcium supplements. Calcium in food doesn’t have an effect on your risk of kidney stones. Continue eating calcium-rich foods unless your doctor advises otherwise. Ask your doctor before taking calcium supplements, as these have been linked to increased risk of kidney stones. You may reduce the risk by taking supplements with meals. Diets low in calcium can increase kidney stone formation in some people.
Ask your doctor for a referral to a dietitian who can help you develop an eating plan that reduces your risk of kidney stones.