Kidney Stones

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Introduction

What are kidney stones?

Kidney stones are small pieces of hard, crystallized material that form in the kidney. Kidney stones are often made up of calcium, but can also contain uric acid or amino acids (proteins). Kidney stones, also called urolithiasis, are a common condition.

One or more kidney stones can form in one or both kidneys. Kidney stones begin as tiny specks and may gradually increase in size. A person with a small kidney stone may not have symptoms and may be unaware of the condition. In some cases, small stones in the urine may pass out of the kidney and move down the ureter, into the bladder, and out of the body without causing pain or serious problems.

There are generally no symptoms of a large kidney stone that remains in the kidney. However, when a large kidney stone moves out of the kidney into the ureter toward the bladder, it causes severe flank, abdominal, and groin pain, called renal colic. Some have described renal colic as the most intense painful experience encountered in life. Other symptoms of a large kidney stone that has moved out of the kidney include blood in the urine, difficulty urinating, and nausea, with or without vomiting.

Kidney stones may be prevented in some cases by ensuring good hydration and with prescribed medication if you are in a high-risk population, such as those with a personal history of kidney stones. Once a stone has developed and causes symptoms, treatment may include hospitalization, pain medication, and certain procedures that remove or crush large stones so that the stone can move more easily out of the body. Small kidney stones may not require treatment.

Most kidney stones pass out of the body in the urine. On occasion, a kidney stone can get stuck in a ureter and result in potentially serious, even life-threatening complications, such as kidney infection and kidney damage. Seek immediate medical care (call 911) if you, or someone you are with, have symptoms of passing a kidney stone, such as severe flank or abdominal pain, not urinating, or bloody urine. Rapid diagnosis and treatment can help reduce the risk of complications.

Symptoms

What are the symptoms of kidney stones?

Small kidney stones or kidney stones that do not move and remain in the kidney may not produce any symptoms. A small kidney stone may pass in the urine out of the body without causing pain or visible blood in the urine.

When a large kidney stone moves out of the kidney and into the ureter, it generally causes severe, sharp and stabbing pain in the flank area of the lower back. This is called renal colic. Renal colic often comes in waves of severe pain that can be accompanied by profuse sweating, restlessness, irritability, nausea and vomiting.

As a kidney stone moves down the ureter toward the bladder, the pain can move from the flank area to the lower abdominal area and into the groin. Pain may also radiate into the testicles or the labia. If the kidney stone is able to pass into the bladder, the pain usually resolves. Once in the bladder, a kidney stone generally is able to move easily out of the bladder, into the urethra, and out of the body during urination.

Symptoms that might indicate a serious condition

Kidney stones can be extremely painful and lead to serious complications, such as kidney infection and kidney damage. Seek immediate medical care (call 911) if you, or someone you are with, have any symptoms of passing a kidney stone including:

  • Bloody or pink-colored urine (hematuria)

  • Dark or tea-colored urine

  • Difficult urination or lack of urination

  • Irritability

  • Nausea and vomiting

  • Restlessness

  • Severe flank pain that can move or radiate to the lower abdomen, groin, labia, or testicles

  • Sweating

Causes

What causes kidney stones?

Kidney stones are tiny hard stones that form in the kidney as a result of a buildup of crystallized material. Kidney stones are often made up of calcium, but they can also contain uric acid or amino acids (proteins). One or more kidney stones can form in one or both kidneys. Kidney stones begin as tiny specks and may gradually increase in size.

What are the risk factors for kidney stones?

A number of factors increase the risk of developing kidney stones. Risk factors include:

  • Dehydration, including long-term mild dehydration, which results in the production of smaller amounts of urine that contain a higher concentration of substances that form kidney stones, such as calcium and amino acids

  • Family history for kidney stone formation

  • Gout (type of arthritis caused by a buildup of uric acid in the joints)

  • High-protein diet

  • Hypertension (high blood pressure)

  • Intestinal malabsorption (Crohn’s disease, postoperative, etc.)

  • Male gender

  • Obesity

  • Personal or family history of kidney stones or certain kidney defects, such as horseshoe kidney

  • Pregnancy

  • Prolonged exposure to a hot climate or high altitudes. People living in these areas lose more body water and produce smaller amounts of urine that contains a higher concentration of substances that form kidney stones, such as calcium and amino acids.

  • Prolonged inactivity, such as being bedridden

  • Urinary tract infection

Reducing your risk of kidney stones

Not all people who are at risk for kidney stones will develop the condition, and not all people who develop kidney stones have risk factors. You may be able to lower your risk of developing kidney stones by:

  • Avoiding dehydration. This means drinking plenty of water and fluids so that your urine is consistently very light or clear in color. If you exercise vigorously or live at a high altitude or in a hot, dry climate, you will need to consistently drink significantly more fluids than a person who has a moderate exercise level or lives in a more tropical climate or lower altitude.

  • Drinking lemonade made from real lemons, which has qualities that may prevent the formation of kidney stones

  • Eating a well-balanced diet that includes moderate portions of protein

  • Following your treatment plan for such conditions as a urinary tract infection and gout

  • Getting regular exercise

  • Maintaining a healthy weight and losing excess weight

  • Taking medications as prescribed to prevent the formation of certain types of kidney stones

Treatments

How are kidney stones treated?

It is common for a person with a small kidney stone to be unaware of the condition. In fact, it may pass out of the body spontaneously without any treatment. Larger kidney stones that move out of the kidney often require treatment.

General treatment of kidney stones

General treatment of kidney stones includes:

  • Drinking fluids to dilute the urine and help flush out a kidney stone

  • Pain medications, which, for large stones, may be given intravenously by emergency care providers

Surgical treatment of kidney stones

If a kidney stone does not pass out of the body with fluids and pain medications, it may have become lodged in the ureter. A variety of procedures may be considered to remove the stone. These include:

  • Cystoscopy, in which specialized instruments are passed into the ureter through the bladder to withdraw a kidney stone that has become lodged in the lower third of the ureter. A similar procedure may be used to remove or crush the kidney stone using a laser or ultrasonic probe.

  • Extracorporeal shock wave lithotripsy, a procedure that is performed for a kidney stone located in the upper ureter or in the kidney. In this procedure, the kidney stone is crushed by a machine using high-energy sound waves (also known as shock waves).

In rare cases in which kidney damage has occurred, it may be necessary to remove the affected kidney. This is called a nephrectomy.

What are the possible complications of kidney stones?

Complications of kidney stones can be serious and life threatening. You can help minimize your risk of serious complications by following the treatment plan your health care professional designs specifically for you. Serious complications of kidney stones include:

  • Adverse effects of treatment

  • Coma

  • Hydronephrosis (buildup of fluid and swelling of the kidney)

  • Kidney failure

  • Kidney infection (pyelonephritis)

  • Permanent kidney damage and loss of normal kidney function

  • Sepsis

  • Ureteropelvic junction obstruction (UPJ obstruction; scarring and obstruction of the ureter that blocks urine flow from the kidney)
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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2019 Jan 5
  1. Kidney Stones. Medline Plus, a service of the National Library of Medicine National Institutes of Health. http://www.nlm.nih.gov/medlineplus/ency/article/000458.htm
  2. Kidney Stones. National Kidney Foundation. http://www.kidney.org/atoz/content/kidneystones.cfm
  3. Kidney Stones in Adults. National Kidney and Urologic Diseases Information Clearinghouse. http://kidney.niddk.nih.gov/kudiseases/pubs/stonesadults/
  4. Bope ET, Kellerman RD (Eds.) Conn’s Current Therapy. Philadelphia: Saunders, 2013
  5. Domino FJ (Ed.) Five Minute Clinical Consult. Philadelphia: Lippincott Williams & Wilkins, 2013.
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