A stone in your kidney is an irregularly-shaped solid mass or crystal that can be as small as a grain of sand up to the size of a golf ball. Depending on the size of your kidney stone (or stones), you may not even realize that you have one. Even small stones can cause extreme pain as they exit your body through your urinary tract. Drinking fluids may help the process, which can take as long as three weeks.
A large kidney stone can get trapped in your ureter (the tube that drains urine from your kidney down to your bladder). When this happens, the stone can cause bleeding and keep urine from leaving your body. You may need surgery for a stone that can not pass on its own.
How common are kidney stones?
Researchers have concluded that about one in ten people will get a kidney stone during their lifetime. Kidney stones in children are far less common than in adults but they occur for the same reasons. They are four times more likely to occur in children with asthma than in children who do not have asthma.
Who is most likely to get kidney stones? What are the risk factors?
Men in their 30s and 40s are most likely to get kidney stones. However, anyone can develop kidney stones.
There are several risk factors for developing kidney stones. These include:
Not drinking enough liquids.
- Having a diet that includes the substances that form the stones (phosphate, for example, is in meat, fish, beans and other protein-rich foods).
- Having a family history of kidney stones.
- Having a blockage in your urinary tract.
Certain medical conditions can also increase your risk of developing stones. This is because they may increase or decrease levels of the substances that make up a kidney stone. These conditions can include:
- Hypercalciuria (high calcium levels in your urine).
- High blood pressure.
- Diabetes.
- Obesity.
- Osteoporosis.
- Gout and cystic fibrosis.
- Kidney cysts.
- Parathyroid disease.
- Inflammatory bowel disease and chronic diarrhea.
Some surgical procedures, including weight loss surgery or other stomach or intestine surgeries.
Some medications can increase your risk of developing a stone. These medications include:
- Diuretics (water pills).
- Calcium-based antacids (used to treat osteoporosis).
- Crixivan® (used to treat HIV infections).
- Topamax® and Dilantin® (used to treat seizures).
- Cipro® (ciprofloxacin, an antibiotic).
- Ceftriaxone (an antibiotic).
Certain foods can also place you at risk of a kidney stone. These foods include:
- Meats and poultry (animal proteins).
- Sodium (diets high in salt).
- Sugars (fructose, sucrose and corn syrup).
- Are kidney stones genetic (hereditary)?
- Yes, kidney stones can run in families.
What is the urinary tract? How does it work?
Your urinary tract is vital to your body because it gets rid of waste and extra fluid. It is made up of both your kidneys, two ureters, your bladder and your urethra. Each organ has an important job (in the following order):
- Kidneys: Your fist-sized, bean-shaped kidneys are located on either side of your spine, below your rib cage. Each day they filter 120 to 150 quarts of your blood to remove waste and balance fluids. Your kidneys make one to two quarts of urine every day.
- Ureters: After your kidney creates urine, the liquid travels through the tube-shaped ureter to the bladder. There is one ureter per kidney. Kidney stones can pass through the ureters or, if they are too big, get stuck in them. You may require surgery if the stone is too large.
- Bladder: Between your hip bones is your bladder, an organ that stores urine. It stretches to hold about one and a half to two cups.
- Urethra: Like a ureter, your urethra is a tube through which urine passes. It is the final stop of the urinary tract where your urine (and a kidney stone) leaves your body. This is called urination.
- How long does it take a kidney stone to form?
- You can have kidney stones for years without knowing they are there. As long as these stones stay in place within your kidney, you will not feel anything. Pain from a kidney stone typically starts when it moves out of your kidney. Sometimes, a stone can form more quickly — within a few months.
Talk with your healthcare provider about your risk factors. They might do a 24-hour urine test to check how quickly you develop stones.
What are the most common types of kidney stones?
The most common type of kidney stone is a calcium oxalate stone. This type happens when calcium and oxalate combine in your urine. It can happen when you have high quantities of oxalate, low amounts of calcium and are not drinking enough fluids.
Stones caused by uric acid are also fairly common. These come from a natural substance called purine, which is a byproduct of animal proteins (meat, chicken and fish).
If I have multiple kidney stones, are they all made of the same substances?
The materials that make up a kidney stone can be different. You could develop a calcium oxalate stone and one made of uric acid.
What are the symptoms of kidney stones?
You can have a stone in your kidney for years and not know it is there. But, when it starts to move or becomes very large, you may have symptoms. Symptoms of a kidney stone include:
Feeling pain in your lower back or side of your body. This pain can start as a dull ache that may come and go. It can also become severe and result in a trip to the emergency room.
- Having nausea and/or vomiting with the pain.
- Seeing blood in your urine.
- Feeling pain when urinating.
- Being unable to urinate.
- Feeling the need to urinate more often.
- Fever or chills.
- Having urine that smells bad or looks cloudy.
Smaller kidney stones may not cause pain or other symptoms. These “silent stones” pass out of your body in your urine.
What are the symptoms of kidney stones in children?
The most common symptoms of kidney stones are blood in the urine or pain. The amount of pain your child experiences and where it hurts depends on where the stone is located and its size. Other symptoms include:
- Severe colicky pain.
- Inability to urinate (when a stone blocks the urinary tract).
- Nausea/vomiting.
- Cloudy, foul-smelling urine, fever, chills or weakness which might be a sign of a serious infection.
- Blood in the urine.
Most pediatric kidney stones remain in the kidney, but up to a third may migrate from the kidney and get stuck in a ureter. Stones that remain in the kidney, although often painless, can be the source of recurrent urinary tract infections. Those that lodge in the ureter can create severe colicky pain.
CAUSES AND RISK FACTORS
What causes kidney stones?
Kidney stones are formed from substances in your urine. The substances that combine into stones normally pass through your urinary system. When they do not, it is because there is not enough urine volume, causing the substances to become highly concentrated and to crystalize. This is typically a result of not drinking enough water. The stone-forming substances are:
- Calcium.
- Oxalate.
- Uric acid.
- Phosphate.
- Cystine (rare).
- Xanthine (rare).
These and other chemicals are some of the waste products that exit your body.
DIAGNOSIS AND TESTS
How are kidney stones diagnosed?
Your healthcare provider will discuss your medical history and possibly order some tests. These tests include:
Imaging tests: An X-ray, CT scan and ultrasound will help your healthcare provider see the size, shape, location and number of your kidney stones. These tests help your provider decide what treatment you need.
Blood test: A blood test will reveal how well your kidneys are functioning, check for infection and look for biochemical problems that may lead to kidney stones.
Urine test: This test also looks for signs of infection and examines the levels of the substances that form kidney stones.
