What are kidney stones?
Kidney stones. They’re small, but they’re mighty. Did you know that more than half a million people head to the emergency room for kidney stones each year?1 You may be wondering how something so little can be so painful. Most kidney stones range in size from a grain of sand to a chickpea. But some can grow to be the size of a golf ball. Obviously, only smaller stones can potentially pass through your urinary tract on their own — but not without quite a bit of pain.2
A kidney stone is a hard mass made up of minerals, salts and chemicals that form inside your kidneys. Specifically, these substances are calcium, oxalate, uric acid, phosphate, cystine and xanthine. They’re all waste products that typically leave your body through urine. But if there’s not enough urine to help carry these waste products out of your body, they can concentrate and crystalize into a tiny little stone.3, 2
Depending on what it’s made of, stones are classified into groups. This helps doctors determine why you got it in the first place and how you might be able to prevent future stones. So, if you pass a stone at home, save it for a doctor’s analysis. The different types of kidney stones are:3, 1
- Calcium stone: This is the most common type of kidney stone. Calcium stones usually show up as calcium oxalate and they form when calcium and oxalate combine in your urine. Calcium oxalate stones are mainly linked to high levels of oxalate, low amounts of calcium and poor fluid intake. A second variation of calcium stones show up as calcium phosphate. These stones are often caused by metabolic conditions (like diabetes) or certain medicines.
- Uric acid stone: Uric acid stones form when you lose too much fluid (think dehydration). That could be from chronic diarrhea, malabsorption or simply not drinking enough water. It’s also common in people with a high-protein diet, metabolic conditions or certain genetic factors.
- Struvite stone: These stones are less common and form when there’s a urinary tract infection. They can grow quickly and may show little or no symptoms.
- Cystine stone: This type of stone is rare and forms in people who have a hereditary condition called cystinuria. It causes your kidneys to release too much of a specific amino acid (cystine).
If your doctor thinks you might have a kidney stone, you’ll likely do some diagnostic tests to determine a final answer. They’re all pretty simple.3
- Blood test: A blood test can tell your doctor if there’s too much calcium or uric acid in your blood, which may indicate the likelihood of a stone. Markers in your blood show your doctor how healthy your kidneys are and can help identify other medical conditions that might be related (or not) to your kidney stone.
- Urine test: This 24-hour collection test could help show if you’re passing a lot of stone-forming minerals and/or not enough stone-preventing substances.
- Imaging: Things like CT scans and ultrasounds can help spot kidney stones (even really small ones).
If you think you might be passing a stone, you’ll likely be asked to urinate through a strainer so you can catch it — even though it might feel a little odd to go to the bathroom with a strainer in hand. But it’s important for your doctor to check what your stone is made of so you can try to prevent future kidney stones.
If you’ve been lucky enough to have never experienced a kidney stone, you might remember less fortunate male friends or family members say it was the worst pain of their lives. Men get pain in their abdomen, lower back and groin as the stone makes its way through their narrow ureter and eventually out into that handy strainer. A kidney stone won’t cause symptoms unless it moves from your kidney and gets lodged in your ureter. There, it could block the flow of urine and cause your kidney to swell and spasm. Symptoms of kidney stones include:4, 3
- Dull or sharp pain in your side, back, belly, groin, testicles or below your ribs
- Trouble, pain or burning while you urinate
- Feeling the need to urinate often or in small amounts
- Bloody urine
- Foul smelling or cloudy urine
- Pink, red or brown urine
- Nausea and vomiting
Keep in mind, kidney stone pain can move around as the stone moves. So, it’s common for the pain to travel around your mid-section and even change in intensity. If you notice some of the symptoms above, or you’re in a ton of pain, call your primary care provider right away.
Anyone can get a kidney stone. And while men are more likely to get them compared to women, we've all got a chance of getting one. That said, there are a few things that can increase your chance of getting one. Some are out of your control, but many are lifestyle changes you can try to make. Here’s what to be aware of:3
- Family or personal history: Some stones could be hereditary, so if mom or dad has had a stone, you’re at a greater risk. Or, if you’ve had one before, you may likely get one again.
- Dehydration: If you don’t drink enough water during the day, you could be creating a comfortable home for a kidney stone to grow.
- Certain diets: Diets high in oxalate, animal protein and sodium could increase your risk.
- Obesity: Weight gain has been linked to kidney stones.
- Digestive diseases and surgery: Things like gastric bypass surgery, inflammatory bowel disease or chronic diarrhea can increase your chances. Basically, anything that changes the way your body digests and absorbs calcium and water could increase the amount of stone-forming substances in your urine.
- Certain medical conditions: Metabolic conditions (like diabetes and cystinuria) or any other factors that affect your body’s ability to metabolize food could increase your risk.
- Certain supplements and medicines: High doses of vitamin C (your body breaks it down into oxalate), excessive use of laxatives, calcium-based antacids, and medicines used to treat depression or migraines could play a part in your risk for getting kidney stones.
You may be starting to see a pattern with certain nutrients and minerals. Water, calcium and oxalate are big players in causing kidney stones. And, you’ve got control over how much goes in your body. Certain factors, like health history, isn’t something you can change, but lifestyle habits are. They’re actually pretty simple — take a look:5
- Reach for water. If you sweat a lot, do hot yoga, sit in saunas or simply enjoy hot summer days, you have to hydrate your body. Activities that make you lose water could make you urinate less, which means less waste leaves your body and those stone-forming substances have time to crystalize.
- Watch your diet. You may want to consider limiting foods high in oxalate and sodium (salt), and avoiding high doses of vitamin C and calcium from supplements (unless recommended by your doctor). On the flipside, make sure you’re getting enough natural calcium from food sources. And, keep an eye on how much animal protein you eat — too much can cause calcium and uric acid to build up in your body.
- Take a look at your medications. Do some research and talk to your doctor to see if any medicine you’re taking could cause kidney stones.
You might not like this answer, but most kidney stones pass on their own. (You can manage pain with medicine while you wait patiently.) But, if you don’t pass it within a few days or you’re still in a lot of pain, see your doctor. You may have to take extra measures to help move the stone along. The longer the stone sits in your urinary tract, the greater the risk for infection.
Treatment is usually only needed when the stone is too big to pass. If that’s the case, you may need to turn to a procedure or even surgery. There are four things your doctor could do:6
- Shock wave lithotripsy: This non-invasive treatment is the most common for small to medium-sized kidney stones in the U.S. It uses high-energy sound waves to break up your stone into smaller pieces (or even dust) so you can pass it.
- Ureteroscopy: For this procedure, your doctor places a flexible scope through your urethra and into your ureter to reach the stubborn stone. If it’s small enough, the stone can be removed using a little basket. If not, your doctor can use a laser to break it up into smaller pieces.
- Percutaneous nephrolithotomy/nephrolithotripsy: If the stone is still too big to pass after one or both treatments above, your doctor can insert a thin tube through your back and into your kidney. Your doctor can either remove it through the tube (nephrolithotomy) or break it up and remove the stone dust (nephrolithotripsy). Don’t worry, you’re put under anesthesia for this one.
- Open surgery: Rarely, if your stone is really big or other treatments didn’t work, you may need your doctor to head in straight through your kidney to finally remove your stone.
Who should I see if I'm concerned about kidney stones?
If you have any symptoms listed above, or you’re concerned about your chances of getting a kidney stone, visit your primary care provider (the doctor or provider you might see for your yearly physical). Bring a list of your symptoms, health history, concerns and questions. Depending on how the conversation goes, you may need a diagnostic test or you might be referred to a urologist.