|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.
|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:
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.
- 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
- Fever and chills if an infection is
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
- Pain accompanied by fever and
- Blood in your urine
- Difficulty passing urine
|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.
Types of kidney stones
Knowing the type of kidney stone helps determine the cause and may give clues on how to reduce your risk of getting more kidney stones. Types of kidney stones include:
- Calcium stones.
kidney stones are calcium stones, usually in the form of calcium
oxalate. Oxalate is a naturally occurring substance found in food.
Some fruits and vegetables, as well as nuts and chocolate, have high
oxalate levels. Your liver also produces oxalate. Dietary factors,
high doses of vitamin D, intestinal bypass surgery and several
metabolic disorders can increase the concentration of calcium or
oxalate in urine. Calcium stones may also occur in the form of
- Struvite stones.
stones form in response to an infection, such as a urinary tract
infection. These stones can grow quickly and become quite large,
sometimes with few symptoms or little warning.
- Uric acid stones.
acid stones can form in people who don't drink enough fluids or who
lose too much fluid, those who eat a high-protein diet, and those
who have gout. Certain genetic factors also may increase your risk
of uric acid stones.
- Cystine stones.
stones form in people with a hereditary disorder that causes the
kidneys to excrete too much of certain amino acids (cystinuria).
- Other stones.
rarer types of kidney stones can occur.
|Factors that increase your risk of developing kidney stones include:
- Family or personal history.
someone in your family has kidney stones, you're more likely to
develop stones, too. And if you've already had one or more kidney
stones, you're at increased risk of developing another.
- Being an adult.
stones are most common in adults age 40 and older, though kidney
stones may occur at any age.
- Being a man.
are more likely to develop kidney stones, although an increasing
number of women are developing kidney stones.
drinking enough water each day can increase your risk of kidney
stones. People who live in warm climates and those who sweat a lot
may be at higher risk than others.
- Certain diets.
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.
body mass index (BMI), large waist size and weight gain have been
linked to an increased risk of kidney stones.
- Digestive diseases and
bypass surgery, inflammatory bowel disease or chronic diarrhea can
cause changes in the digestive process that affect your absorption
of calcium and water, increasing the levels of stone-forming
substances in your urine.
- Other medical conditions.
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 tests.
tests may reveal too much calcium or uric acid in your blood. Blood
test results help monitor the health of your kidneys and may lead
your doctor to check for other medical conditions.
- Urine tests.
of your urine, such as the 24-hour urine collection, may show that
you're excreting too many stone-forming minerals or too few
- Imaging tests.
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 computerized tomography (CT) that may reveal even tiny
stones. Other imaging options include an ultrasound, a noninvasive
test, and intravenous pyelography, which involves injecting dye into
your arm vein and taking X-rays as the dye travels through your
kidneys and bladder.
- Analysis of passed stones.
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:
Large stones and those that cause symptoms
- Drinking water.
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
- Pain relievers.
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
- Medical therapy.
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.
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:
- Using sound waves to
break up stones.
certain kidney stones — depending on size and location — your
doctor may recommend a procedure called extracorporeal shock
wave lithotripsy (SWL). SWL uses sound waves to create strong
vibrations (shock waves) that break the stones into tiny pieces
that can be passed in your urine. The procedure lasts about 45
to 60 minutes and can cause moderate pain, so you may be under
sedation or light anesthesia to make you comfortable. SWL can
cause blood in the urine, bruising on the back or abdomen,
bleeding around the kidney and other adjacent organs, and
discomfort as the stone fragments pass through the urinary
- Surgery to remove very
large stones in the kidney.
procedure called percutaneous nephrolithotomy (nef-row-lih-THOT-uh-me)
involves surgically removing a kidney stone using small
telescopes and instruments inserted through a small incision in
your back. You'll receive general anesthesia during the surgery
and be in the hospital for one to two days while you recover.
Your doctor may recommend this surgery if SWL was unsuccessful
or if your stone is very large.
- Using a scope to remove
remove a smaller stone in your ureter or kidney, your doctor may
pass a thin lighted tube (ureteroscope) equipped with a camera
through your urethra and bladder to your ureter. Once the stone is
located, special tools can snare the stone or break it into pieces
that will pass in your urine. Your doctor may then place a small
tube (stent) in the ureter to relieve swelling and promote healing.
You may need general or local anesthesia during this procedure.
- Parathyroid gland surgery.
calcium stones are caused by overactive parathyroid glands,
which are located on the four corners of your thyroid gland,
just below your Adam's apple. When these glands produce too much
parathyroid hormone (hyperparathyroidism), your calcium levels
can become too high and kidney stones may form as a result.
Hyperparathyroidism sometimes occurs when a small, benign tumor
forms in one of your parathyroid glands or you develop another
condition that leads these glands to produce more parathyroid
hormone. Removing the growth from the gland stops the formation
of kidney stones. Or your doctor may recommend treatment of the
condition that's causing your parathyroid gland to overproduce