Kidney stones

Kidney stones are solid masses of tiny crystals that form inside the kidneys. These crystals can stick together and grow into stones that may stay in the kidney or travel through the urinary tract. Also called renal stones or nephrolithiasis, the stones may block the flow of urine, causing sudden, severe pain. Some stones pass on their own, while others need medical care.

At Penn Medicine, our kidney stone clinic offers advanced treatments like extracorporeal shock wave lithotripsy (ESWL). This noninvasive procedure uses high-energy sound waves to break a stone into tiny pieces. Because it’s done from outside the body, there are no cuts or incisions, and the fragments can pass naturally in your urine. Our urinary stones care and kidney medicine specialists are also national leaders in the field, using the latest research to help you pass or remove stones and reduce the risk of stones returning.

You might not feel a stone while it’s inside your kidney. Most kidney stone symptoms start when the stone moves into the ureter, the tube that carries urine to the bladder. If a stone gets stuck, it can block urine flow and cause intense pain. Kidney stone pain often comes in waves and may change location as the stone moves through the urinary tract.

Common signs of kidney stones include:

• Sharp pain in the side, back, lower abdomen, or groin
• Burning or pain while urinating
• Blood in the urine or abnormal urine color
• Feeling the need to urinate often
• Fever or chills if an infection is present
• Upset stomach, nausea, or vomiting

Kidney stones form for different reasons. Knowing the type you have helps your care team determine the cause and guide treatment. If you pass a stone and can save it, bring it to your provider for analysis.

The main types include:

• Calcium stones are the most common and happen when calcium mixes with substances like oxalate, found in foods like spinach, nuts, and chocolate. 
• Uric acid stones occur in people who are dehydrated, eat large amounts of animal protein, or have conditions like gout.
• Struvite stones often form after a urinary tract infection (UTI), can grow quickly and become large, sometimes forming staghorn stones that take the shape of the inside of the kidney. 
• Cystine stones are caused by a rare genetic disorder that allows too much amino acid to leak into the urine.

There isn’t always one single reason why stones form, but the biggest risk factor is not drinking enough fluids. If you make less than 32 ounces (1 liter) of urine a day, you’re more likely to develop a stone. When your urine is too concentrated, minerals like calcium and uric acid can’t dissolve properly. 

Other factors that may increase risk include:

• Diets high in salt or animal protein
• Medical conditions like hyperparathyroidism 
• Digestive diseases that affect nutrient absorption
• Some medications
• Family history of kidney stones

Kidney stones can be incredibly painful, but they don’t have to be a permanent part of your life. The kidney medicine specialists at Penn Medicine can help you find relief and create a plan to prevent recurrence in the future.

We offer:

• Advanced ESWL technology: Our experts use the latest shock wave technology to provide a noninvasive experience, meaning no hospital stays and a faster return to your daily life.
• Leading research: We lead clinical trials that investigate why stones form and provide access to the latest breakthroughs before they are available elsewhere.
• Complex stone expertise: We’re among the few health care centers in the region skilled in removing very large or staghorn stones through tiny, minimally invasive incisions, so even the most difficult cases are handled with care.