What are kidney stones?

A kidney stone is a small mass of minerals, salts and other materials that crystallize inside the kidney when the urine becomes concentrated.

Kidney stones can form anywhere in the urinary track including the bladder.

Common related conditions
Hematuria (Blood in Urine)

Types of kidney stones

  • Calcium stones — dietary factors may increase the amount of calcium oxalate in the body, which can lead to calcium stones, the most common type of kidney stone.
  • Struvite stones — can form quickly after a UTI.
  • Uric acid stones — people who don’t drink much water or eat a high protein diet are more likely to develop uric acid stones.
  • Cystine stones — hereditary disorders where the kidneys excrete excessive amounts of amino acids are a common cause of cystine stones.

Causes of kidney stones

Kidney stones can be caused by a variety of factors including:

  • Low urine volume — concentrated urine contains more salts, minerals and uric acid, which can form into hard stones.
  • Diet — diets high in animal proteins, salt or sugar raise acid levels in the body, which create an ideal environment for kidney stones to form.
  • Obesity — being overweight can increase the acid levels in the urine, which can lead to kidney stone formation.

Risk factors for kidney stones

You are more likely to develop kidney stones if you have any of the following risk factors:

  • Have a family history of kidney stones
  • Frequently dehydrated
  • Overweight or obese
  • Consume a diet high in protein, sodium and sugar
  • History of digestive diseases surgery, such as gastric bypass surgery, inflammatory bowel disease or chronic diarrhea

Symptoms of kidney stones

Many people are unaware that they have kidney stones until the stones pass into the ureter.

Once this occurs, you may feel the following symptoms:

  • Severe pain in the side and back
  • Cloudy urine
  • Persistent need to urinate
  • Blood in the urine (hematuria)
  • Pain on urination
  • Nausea vomiting
  • Fever and chills

Diagnosis of kidney stones

Kidney stones can be diagnosed during a physical exam. Your doctor will take a full medical history and order tests to confirm the diagnosis.

Diagnostic tests include:

  • Blood tests —can show how much calcium or uric acid is in the blood.
  • Urinalysis — can show if you have too many stone-forming minerals in your urine.
  • Diagnostic imaging — tests such as an x-ray or CT scan can show if there are kidney stones in the urinary tract.
  • Passed stone analysis — if you have recurrent kidney stones, your stones may be analyzed to determine the cause.

Treatment for kidney stones

Treatment for kidney stones will vary depending on the size, location and type of stone. Small stones can be passed without medical intervention. Your doctor may recommend drinking lots of water and taking pain relievers until the stone passes. In some cases, the doctor may give you a prescription medication (alpha blocker) that will help you pass the stone with less pain.

For patients with large stones and severe symptoms, more advanced treatment is necessary. If you have been treated by your primary care doctor, you will be referred to a urologist for care. Procedures to treat kidney stones include:

  • Extracorporeal shock wave lithotripsy (ESWL) — uses sound waves to break up stones in the kidney; smaller stones can more easily pass down the ureter into the bladder and out of the body.
  • Tunnel surgery (percutaneous nephrolithotomy) — procedure to remove large stones in the kidney through an incision in your back.
  • Ureteroscopy or cystoscopy — stones are broken into smaller pieces that can pass in the urine.

Recovery from kidney stones

Many people do not have another kidney stone after the initial stone. Others have recurrent stones. If you have recurrent stones, it is important to make lifestyle changes to prevent future stones.

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