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.
See also: Cystinuria
Kidney stones are common. Some types run in families. They often occur in premature infants.
There are different types of kidney stones. The exact cause depends on the type of stone.
Stones can form when urine contains too much of certain substances. These substances can create small crystals that become stones. The stones take weeks or months to form.
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 of urine a day. That's slightly more than a quart.
You may not have symptoms until the stones move down the tubes (ureters) through which urine empties into your bladder. When this happens, the stones can block the flow of urine out of the kidneys.
The main symptom is severe pain that starts suddenly and may go away suddenly:
Other symptoms can include:
The health care provider will perform a physical exam. The belly area (abdomen) or back might feel sore.
Tests that may be done include:
Stones or a blockage can be seen on:
Treatment depends on the type of stone and the severity of your symptoms.
Kidney stones that are small usually pass on their own. When the stone passes, the urine should be strained so the stone can be saved and tested.
Drink at least 6 - 8 glasses of water per day to produce a large amount of urine. See also: Kidney stones - self-care
Pain can be severe enough to need narcotic pain relievers. Some people with severe pain from kidney stones need to stay in the hospital. You may need to get fluids through a vein (intravenous).
Depending on the type of stone, your doctor may prescribe medicine to decrease stone formation or help break down and remove the material that is causing the stone. Medications can include:
Surgery is usually needed if:
Today, most treatments are much less invasive than in the past.
See also: Kidney stones - what to ask your doctor
Kidney stones are painful but usually can be removed from the body without causing permanent damage.
Kidney stones often come back, especially if the cause is not found and treated.
If treatment is significantly delayed, damage to the kidney or other serious complications can occur.
Call your health care provider if you have symptoms of a kidney stone.
Also call if symptoms return, urination becomes painful, urine output decreases, or other new symptoms develop.
If you have a history of stones, drink plenty of fluids (6 - 8 glasses of water per day) to produce enough urine. Depending on the type of stone, you might need medications or diet changes to prevent the stones from coming back.
Renal calculi; Nephrolithiasis; Stones - kidney
Curhan GC. Nephrolithiasis. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 128.
Finkelstein VA. Strategies for preventing calcium oxalate stones. CMAJ. 2006;174:1407-1409.
Pietrow PK, Preminger GM. Evaluation and medical management of urinary lithiasis. In: Wein AJ, ed. Campbell-Walsh Urology. 9th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 43.
Updated by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; Scott Miller, MD, Urologist in private practice in Atlanta, Georgia. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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