Kidney stone basics: Different types and how to prevent them

The way symptoms for a kidney stone begin are almost always the same: Quick, sudden onset, ten-out-of-ten pain. It’s usually a stabbing, sharp pain in the back flank. It might be accompanied by nausea and/or bloody urine. 

The symptoms are clear, immediate, usually very intense, and if you know, you know: It’s a kidney stone. In fact, according to the National Kidney Foundation, more than a half a million people are seen in emergency departments each year for kidney stones. So, what are they, how does this happen—and what do you do to prevent or pass them safely?

What are kidney stones?

The kidneys are organs that help filter waste out of your urine.  Sometimes, you get a buildup of chemicals in your urine that can bind together and form a stone when you don’t have enough water to dilute them. Sometimes these stones hang out in the kidney and never cause an issue. But sometimes they jog loose and then pass through the ureter, a tube that connects the kidney to the bladder. This passing can be incredibly painful. And sometimes they get stuck, backing up urine into the bladder, which can also be painful and cause damage.

What are the types of kidney stones?

The three most common kidney stone types are made of:  

• Calcium oxalate: This is the most common type of kidney stone, and it forms when calcium and oxalate combine in the urine. 
• Calcium phosphate: This is less common, and can be caused by medications that change the pH level of your urine, making it more alkaline, or less acidic, than normal. 
• Uric acid: This type of kidney stone is often linked to high meat/seafood diets, which increase uric acid. Gout and diabetes are also risk factors for these types of stones. 

There are two lesser-common stone types as well: 

• Struvite: These types of stones are more common in women, and are caused by upper urinary tract infections.  
• Cystine: These types of stones are rare, and caused by a genetic disorder, called cystinuria.  

Knowing which type of kidney stone you have can help shed light on whether there is a genetic component to your stones, or you need some kind of dietary change to avoid getting another.  

How do I prevent kidney stones?

First things first, an ounce of prevention is worth a pound of cure. While some people may have a genetic predisposition to kidney stones—and men experience them more often than women—there are ways you can mitigate your risk.  

Stay hydrated 

Of the first ten steps you take to prevent kidney stones, nine of them should be drinking water. For people who have kidney stones that means two to three liters of water a day. You want your kidneys to constantly be flushed. That way, if you happen to be forming crystals in your urine, they never get a chance to form into a larger stone that causes you bigger problems. And note that caffeinated or alcoholic drinks can contribute to dehydration. It doesn’t mean you can’t have them, it just means they don’t count toward your total water intake. Most people underestimate their fluid intake, so log it for a while if you’re not sure. You may be surprised. 

Add citrus to your water 

If you dislike drinking water, or want to change things up, adding a squeeze of lemon or lime or drinking real lemonade can help. Nephrologists sometimes treat kidney stones with citric acid, and you can add that right into your diet yourself. Sound like magic? It’s science! Citric acid binds to calcium in the urine, which then means it’s too tied up to form stones. It may also change the pH level of urine, which can be beneficial for preventing certain types of stones.

Reduce sodium intake

When you eat a lot of salt, the amount of calcium you excrete in your urine goes up. This is a main component in the most common kidney stones. It can be hard to reduce intake when it makes food so tasty, but there are lots of great salt alternatives to boost flavor in your favorite dishes.

Maintain a healthy weight

Obesity is a risk factor for kidney stones. The reason is that a higher body weight can change some of the metabolic systems that would contribute to an increase in oxalate and uric acid, which are components of calcium oxalate kidney stones. 

What are the stages of a kidney stone passing?

Kidney stones form in the kidney. Sometimes those stones hang out there without causing any issues. Dehydration may trigger movement of the stone, as does the natural movement of urine from the kidney to the bladder, which travels inside a tube called the ureter. Once the stone is in the ureter, you’ll experience the classic stabbing pain. This is also where a stone can get stuck. Gravity helps move the stone along as well. Eventually, the stone drops into the bladder, and a person passes the stone with their urine through the urethra. 

Can I pass a kidney stone at home?

While it is true that people do pass kidney stones at home, it’s still recommended you get seen—and odds are, you’ll want to be seen. That’s because, for most people, once the pain of a kidney stone hits, it’s uncontrollable without IV pain medication. Typically, people proceed most directly to the emergency room—and that’s what's recommended, because the symptoms are sometimes indistinguishable from a ruptured appendix. If a stone gets stuck, you’ll need surgical intervention, as you could be at risk for sepsis or acute renal failure.  

Additionally, there isn’t a good way to rule out other conditions without some imaging, so it’s good to confirm it is indeed a kidney stone and the size of it. Sometimes, if the stone is small enough and the pain is controlled, a patient will be sent home to pass the stone on their own. 

What can I expect after passing a kidney stone?

If you end up passing a stone at home after being evaluated by a physician, they may ask you to use a strainer when you urinate to catch the stone. This allows you to save the stone and bring it to your doctor—this could be primary care, or a follow-up with nephrology—to do a stone analysis.  These stone analyses can shed light on the potential cause of the stone. 

The pain typically ends after you pass the stone, though you may be a little tender and tired. The bloody urine should also clear up within a day or so. Call your physician if you are struggling with any recovery symptoms so you can be evaluated. 

If you have experienced more than one kidney stone, it may be worth talking to a nephrologist. They can help you determine the causes and if you need any additional changes to your diet, medications to help prevent future stones, and more. 

Can you die from a kidney stone? 

Given the pain level, it’s not surprising people ask this question. The short answer is most people pass a kidney stone, with or without surgical intervention, and return to their regular lives. 

But occasionally the size of a stone causes it to get stuck in the ureter. The stone can get infected, causing sepsis, and you can also develop acute renal failure, all of which are dangerous. These dangers can be avoided with surgical intervention, so this is why it is always a good choice to be evaluated by a medical professional if you think you have a kidney stone. 

Follow-up kidney stone care

If you’ve passed a stone and saved it, you can bring it to your primary care doctor or a nephrology specialist to have a stone analysis done in the lab. The makeup of the stone could provide clues into what may have caused it, and more importantly, what you can do to prevent another from happening. If you’ve had more than one stone, it’s a good idea to find a nephrology specialist to consult to maintain your best health.