A kidney stone is a solid mass made up of tiny crystals. One or more stones can be in the kidney or ureter at the same time.

Causes

Kidney stones are common. Some types run in families. They may occur at any age, including in premature infants.

There are different types of kidney stones. The cause depends on the type of stone.

Stones can form when urine contains too much of certain substances that form crystals. These crystals can develop into stones over weeks or months.

• Calcium stones are most common. They are most likely to occur in men between ages 20 to 30. Calcium can combine with other substances to form the stone.
• Oxalate is the most common of these substances. Oxalate is present in certain foods such as spinach. It is also found in vitamin C supplements. Diseases of the small intestine increase your risk for these stones.

Nephrolithiasis

Kidney stones result when urine becomes too concentrated and substances in the urine crystalize to form stones. Symptoms arise when the stones begin to move down the ureter causing intense pain. Kidney stones may form in the pelvis or calyces of the kidney or in the ureter.

Calcium stones can also form by combining with phosphate or carbonate.

Other types of stones include:

• Cystine stones can form in people who have cystinuria. This disorder runs in families. It affects both men and women.
• Struvite stones are mostly found in men or women who have repeated urinary tract infections. These stones can grow very large and can block the kidney, ureter, or bladder.

  Urinary tract infections

  A urinary tract infection, or UTI, is an infection of the urinary tract. The infection can occur at different points in the urinary tract, including...

  

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• Uric acid stones are more common in men than in women. They can occur with gout or after receiving chemotherapy for some types of cancer.
• Other substances, such as certain medicines, also can form stones.

Cystinuria

Cystinuria is a disorder characterized by cystine stones in the kidney, ureter, and bladder. A genetic abnormality results in abnormal transport of amino acids in the kidney. The high levels of the amino acid cystine in the urine lead to stone formation.

The biggest risk factor for kidney stones is not drinking enough fluids. Kidney stones are more likely to occur if you make less than 1 liter (32 ounces) of urine a day.

Symptoms

You may not have symptoms until the stone moves down the tube (ureters) through which urine empties into your bladder. When this happens, the stone can block the flow of urine out of the kidneys, causing pain.

The main symptom is severe pain that starts and stops suddenly:

• Pain may be felt in the belly area or side of the back.
• Pain may move to the groin area (groin pain), testicles (testicle pain) in men, and labia (vaginal pain) in women.

Kidney pain

A kidney stone is a solid piece of material that forms in a kidney. Kidney stones may be the size of sand or gravel, as large as a pearl, or even larger. A stone can block the flow of urine and cause great pain.

Other symptoms can include:

• Abnormal urine color
• Blood in the urine

  Blood in the urine

  Blood in your urine is called hematuria. The amount may be very small and only detected with urine tests or under a microscope. In other cases, the...

  

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• Chills
• Fever
• Nausea and vomiting

  Nausea and vomiting

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Exams and Tests

Your health care provider will perform a physical exam. The belly area (abdomen) or back might feel sore.

Tests that may be done include:

• Blood tests to check calcium, phosphorus, uric acid, and electrolyte levels
• Kidney function tests
• Urinalysis to check for crystals and red blood cells in urine

  Urinalysis

  Urinalysis is the physical, chemical, and microscopic examination of urine. It involves a number of tests to detect and measure various compounds th...

  

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• Examination of the stone to determine the type

Stones or a blockage can be seen on:

• Abdominal CT scan

  Abdominal CT scan

  An abdominal CT scan is an imaging test that uses x-rays to create cross-sectional pictures of the belly area. CT stands for computed tomography....

  

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• Abdominal x-rays

  Abdominal x-rays

  An abdominal x-ray is an imaging test to look at organs and structures in the abdomen. Organs include the liver, spleen, stomach, and intestines. Wh...

  

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• Kidney ultrasound

  Kidney ultrasound

  Abdominal ultrasound is a type of imaging test. It is used to look at organs in the abdomen, including the liver, gallbladder, pancreas, and kidneys...

  

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• Retrograde pyelogram

Treatment

Treatment depends on the type of stone and the severity of your symptoms.

Kidney stones that are small most often pass through your system on their own.

• Your urine should be strained so the stone can be saved and tested.
• Drink at least 6 to 8 glasses of water per day to produce a large amount of urine. This will help the stone pass.
• Pain can be very bad. Over-the-counter pain medicines (for example, ibuprofen and naproxen), either alone or along with narcotics, can be very effective.

Some people with severe pain from kidney stones need to stay in the hospital. You may need to get fluids through an IV into your vein.

For some types of stones, your provider may prescribe medicine to prevent stones from forming or help stones pass through your urinary system. These medicines can include:

• Allopurinol (for calcium oxalate or some uric acid stones)
• Antibiotics (for struvite stones)
• Phosphate solutions
• Potassium citrate
• Water pills (thiazide diuretics)
• Tamsulosin to relax the ureter and help the stone pass

Surgery is often needed if:

• The stone is too large to pass on its own.
• The stone is growing.
• The stone is blocking urine flow and causing an infection or kidney damage.
• The pain cannot be controlled.
• If there is a urinary tract infection or fever.

Today, most treatments are much less invasive than in the past.

• Lithotripsy is used to remove stones slightly smaller than one half an inch (1.25 centimeters) that are located in the kidney or ureter. It uses sound or shock waves to break up stones into tiny fragments. Then, the stone fragments leave the body in the urine. It is also called extracorporeal shock-wave lithotripsy or ESWL.

  Lithotripsy

  Lithotripsy is a procedure that uses shock waves to break up stones in the kidney and parts of the ureter (tube that carries urine from your kidneys ...

  

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• Procedures performed by passing a special instrument through a small surgical cut in your skin on your back and into your kidney or ureters are used for large stones, or when the kidneys or surrounding areas are incorrectly formed. The stone is removed with a tube (endoscope).

  Passing a special instrument

  Percutaneous (through the skin) urinary procedures help drain urine from your kidney and get rid of kidney stones.

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• Ureteroscopy may be used for stones in the lower urinary tract. A laser is used to break up the stone.
• Rarely, open surgery (nephrolithotomy) may be needed if other methods do not work or are not possible.

Lithotripsy procedure

Extracorporeal shock wave lithotripsy (ESWL) is a procedure used to shatter simple stones in the kidney or upper urinary tract. Ultrasonic waves are passed through the body until they strike the dense stones. Pulses of sonic waves pulverize the stones, which are then more easily passed through the ureter and out of the body in the urine.

Talk to your provider about what treatment options may work for you.

You will need to take self-care steps. Which steps you take depend on the type of stone you have, but they may include:

• Drinking extra water and other liquids
• Eating more of some foods and cutting back on other foods
• Taking medicines to help prevent stones
• Taking medicines to help you pass a stone (anti-inflammatory drugs, alpha-blockers)

Outlook (Prognosis)

Kidney stones are painful, but most of the time can be removed from the body without causing lasting damage.

Kidney stones often come back. This occurs more often if the cause is not found and treated.

You are at risk for:

• Urinary tract infection (UTI)
• Kidney damage or scarring if treatment is delayed for too long

Possible Complications

Complications of kidney stones may include the obstruction of the ureter (acute unilateral obstructive uropathy).

When to Contact a Medical Professional

Contact your provider if you have symptoms of a kidney stone:

• Severe pain in your back or side that will not go away
• Blood in your urine
• Fever and chills
• Vomiting

  Vomiting

  Nausea is feeling an urge to vomit. It is often called "being sick to your stomach. "Vomiting or throwing-up forces the contents of the stomach up t...

  

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• Urine that smells bad or looks cloudy
• A burning feeling when you urinate

If you have been diagnosed with blockage from a stone, passage must be confirmed either by capture in a strainer during urination or by follow-up x-ray. Being pain free does not confirm that the stone has passed.

Prevention

If you have a history of stones:

• Drink plenty of fluids (6 to 8 glasses of water per day) to produce enough urine.
• You may need to take medicine or make changes to your diet for some types of stones.
• Your provider may want to do blood and urine tests to help determine the proper prevention steps.

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