What Are Kidney Stones?
Kidney stones (also known as nephrolithiasis or urolithiasis) form in your urinary system when you have high levels of certain substances in your urine that crystalize and stick together. There are several types of kidney stones and causes for them.
While some stones stay in the kidneys and go undetected, others leave and have the potential to cause significant pain and, in some cases, complications. Depending on your situation, a kidney stone may pass in your urine or you may require surgical treatment to remove it.
Kidney Stone Symptoms
If you have a kidney stone that moves inside your kidney, through your urinary tract, or gets stuck in your ureter (the tube that urine passes through from the kidney to the bladder), you may experience:
- mild to severe pain in your back or side (below your ribs), which can come in waves and radiate to your lower abdomen and groin,
- pain at the tip of the penis, if you are a man,
- painful urination,
- urine that has blood in it or smells foul,
- urinating more often and in smaller amounts,
- nausea and vomiting, and
- fever and chills, which may indicate you have an infection.
It is also possible to not show symptoms while the stones are inside your kidneys.
When you pass a kidney stone, you may notice it in your urine stream. Its small appearance may look like a grain of sand or a small pebble.
Find a Doctor
Kidney Stone Diagnosis
If you experience sudden pain, blood in your urine, or other kidney stone symptoms, our urology experts at University of Utah Health can perform a physical exam and order diagnostic tests. These may include:
- Imaging tests — These will show us if you have a kidney stone, including its location, size, and if there’s more than one. While X-rays and ultrasounds can be used in some cases, a CT (computed tomography) scan of your abdomen is generally the most reliable test overall.
- Urine tests — These will look for signs of infection and the levels of substances that can form stones. We may perform urine tests before and after you pass a stone.
- Blood tests — These will show how well your kidneys are functioning, look for signs of infection, and look for other problems that can lead to kidney stones.
- Stone analysis — After you pass a stone or after we remove it surgically, we can test it to find out what type of stone it is. Identifying the stone will guide our preventive measures and treatment for future stones.
Since stones can stay in your kidneys for years without causing symptoms, it’s also possible for you to learn that you have a kidney stone while receiving an imaging test for another reason. These are called silent kidney stones.
Types of Kidney Stones and Their Causes
There are four main types of kidney stones:
- Calcium stones (80 percent of stones)
- Uric acid stones (5 to 10 percent of stones)
- Struvite stones (10 percent of stones)
- Cystine stones (less than 1 percent of stones)
While causes can vary for each type of stone, you may be at a greater overall risk for developing kidney stones if:
- You or someone in your family had kidney stones in the past.
- You consistently have a low volume of urine or your urine is concentrated or dark in color.
- You have certain medical conditions.
- You take certain medications or supplements.
Calcium stones are the most common type of kidney stones. They are usually made of calcium and oxalate (a natural substance in many foods), but they can also be made of calcium and phosphate.
A calcium oxalate stone can form when you have too much calcium or oxalate in your urine. Common causes are:
- dietary factors,
- chronic diarrhea,
- intestinal bypass surgery, and
- certain metabolic disorders.
A calcium phosphate stone can form when your urine contains too much calcium, too much phosphate, or too little citrate (a substance found in supplements and some medications). This can happen if you:
- have a kidney condition called renal tubular acidosis,
- make too much of the parathyroid hormone, or
- have urinary tract infections.
Uric Acid Stones
A uric acid stone forms when your urine has a low pH (is too acidic) or contains too much uric acid. This can happen if you:
- have gout,
- have type 2 diabetes,
- are overweight,
- have chronic diarrhea,
- eat a lot of animal protein,
- have certain genetic factors, or
- are on chemotherapy.
Uric acid stones are made of crystalized uric acid (a natural waste product from digesting food) alone or along with calcium. They make up about 5 to 10 percent of stones, and are more common in men. It is possible for uric acid stones to dissolve if your urine pH is raised.
A struvite stone can form when you have an infection, such as a urinary tract infection (UTI), that causes your urine to have a more alkaline pH (less acidic). Struvite stones are made of magnesium, ammonium, and phosphate. They often grow quickly and can cause damage if they become too large.
Around 10 percent of kidney stones are struvite stones, and they are more common in women. Your risk of developing struvite stones is higher if you have chronic UTIs.
A cystine stone may form if you have a genetic disorder called cystinuria. Cystinuria causes your kidneys to release too much cystine (a kind of amino acid) into your urine, which can bind into stones. Cystine stones are rare, but often start to form in childhood if you have cystinuria.
We will often treat cystine stones by increasing fluids and prescribing medication. However, larger cystine stones may need to be surgically removed to prevent damage.
Kidney Stone Treatment
After we assess your condition, we will recommend kidney stone treatment options based on your unique situation. This may include the following non-surgical or surgical methods:
- passing a kidney stone at home,
- shock wave lithotripsy (a procedure that uses ultrasound energy to break a kidney stone into smaller fragments),
- ureteroscopy with laser lithotripsy (a minimally invasive procedure that breaks up your stone using a small laser fiber),
- percutaneous nephrolithotomy (a minimally invasive procedure that uses ultrasonic energy to break up a large kidney stone before removing it).
Make an Appointment with Our Urologists
Please contact the University of Utah Health urology team at 801-213‑2700 if you would like to schedule an appointment. Wherever you are in your journey—whether you are starting to have symptoms, need a follow-up after seeing another provider, or want to prevent a reoccurrence—we are here to provide the quick care and expertise you need.