Kidney Stones
(Renal Calculi, Nephrolithiasis)
Pronounced: REE-nul KALK-you-lie
Definition
Kidney stones are pieces of a stone or crystal-like material that form inside the kidneys or urinary tract. The kidneys are two bean-shaped organs located in the lower back. Their main function is to remove waste from the body and to balance the water and electrolyte content of the blood by filtering the salt and water in the blood. The waste and water excreted by the kidneys combine to form urine.
There are several types of kidney stones. The most common type contains mostly calcium along with phosphate or oxalate. Others may contain uric acid, struvite, and/or cystine.
Kidney Stone
© 2008 Nucleus Medical Art, Inc.
Causes
Approximately 50% of kidney stones are due to unknown causes. Some of the known causes include:
- Chemotherapy for cancer (ie, uric acid stone)
- Too much oxalate in urine (hyperoxaluria)
- Too little magnesium in urine (hypomagnesemia)
- Too much calcium in the urine (hypercalciuria)
- Too much calcium in the blood (hypercalcemia)
- Too little citrate in the urine (hypocitraturia)
- Tiny bacteria around which a stone can form
- Too much uric acid in the urine (hyperuricuria, gout )
- Bacteria that produce enzymes that increase the amount of ammonia and struvite in the urine, allowing struvite stones to form
- An inherited abnormality in the way the body handles cystine
- Certain medications (such as indinavir)
- Retention of urine
Risk Factors
A risk factor is something that increases your chance of getting a disease or condition. Risk factors for kidney stones include:
- Race: White
- Sex: male
- Age: 20 to 50 years old
- Geographical location (residents of the Southeast United States have an increased risk)
- Family members who have had kidney stones or gout
- Previous kidney stones
- Taking calcium supplements, vitamin D, or vitamin C in excessive doses
- Pregnancy
- Low birth weight babies receiving intravenous feedings
- Fasting
- Other medical conditions, including:
- Immobility, paralysis , being bedridden
-
Medications, including:
- Several drugs used in the treatment of AIDS
- Cancer chemotherapy agents
- Diuretics
- Antacids
- Previous intestinal bypass surgery
- Reduced fluid intake or increased fluid loss in hot weather (dehydration)
- Urinary tract obstruction or failure to empty the bladder (eg, spinal cord injury, diabetes, prostate disease, urethral stricture)
- Foreign material in the urinary tract, including catheters and ureteral stents
Symptoms
Occasionally, kidney stones do not cause symptoms, and they leave the body in the urine. Kidney stones may, however, cause severe pain.
Symptoms include:
- Sharp, stabbing pain in the lower back that may occur every few minutes lasting from 20 minutes to one hour
- Pain in the lower abdomen and groin area, labia, or testicles
- Nausea, vomiting, or diarrhea
- Blood in the urine
- Frequent urge to urinate
- Burning pain during urination
Kidney stones may also cause fevers or urinary tract infections. Sometimes, patients may have repeated urinary tract infections because of kidney stones.
Diagnosis
The doctor will ask about your symptoms and medical history, and perform a physical exam.
Tests may include:
- Urinalysis—to look for blood, pus, bacteria, and crystals in the urine
- Blood tests—to check kidney function, calcium, and uric acid levels
- Urine culture—if infection suspected
- Spiral CT scan—a type of x-ray that uses a computer to make pictures of the inside of the kidney
- Ultrasound —a test that uses sound waves to examine the kidneys
- Intravenous pyelogram (IVP) — special x-ray that produces images of the urinary system (less commonly used today)
- 24-hour urine—to check levels of many factors, including calcium, phosphorus, uric acid, oxalate, and citrate
Treatment
Treatment depends on the size and location of the kidney stone. Treatment may include the following:
Water
For small kidney stones, drinking at least two or three quarts of water a day helps the body pass the stone in the urine. The doctor may provide a special cup or strainer to catch the stone when it passes so that it can be analyzed. If you are having a hard time keeping fluids down, you may need to be hospitalized to receive intravenous fluids.
Medications and Nerve Stimulation
You can take pain medication (ketorolac, an NSAID, or narcotic pain medications) as needed. In addition, you may need intravenous or intramuscular pain medication.
There is also recent evidence that medications commonly used to treat high blood pressure—calcium channel blockers and alpha blockers—may facilitate the passage of kidney stones. * 1
Current research suggests that transcutaneous electrical nerve stimulation (TENS), which applies low-voltage electrical current to electrodes pasted on the skin (to the side of the abdomen and back, in this case) might also be effective in relieving pain. * 2
Surgery
Surgery for stone removal may be necessary if it is:
- Very large or growing larger
- Causing continued bleeding or damage to the kidney
- Causing infection
- Blocking the flow of urine
Types of surgery include:
- Ureteroscopy and stone basketing or laser lithotripsy—This involves a narrow camera that is slipped up the urethra, into the bladder, and into the ureter. A tiny basket may be used to snare the stone. If needed, the stone can be broken into fragments or dissolved with a laser. Any small fragments can be removed with a basket.
- Stent placement—If the ureter is obstructed, a tiny tube may be placed in the ureter to allow urine to pass, and to try to avoid kidney damage. If there is an active infection, a stent may be needed to allow the infection to clear before proceeding with surgery to remove the stone. It is very important that all stents be removed. Stents are temporary, and will form more stones and cause infection if left in place for prolonged periods.
- Extracorporeal shock wave lithotripsy (ESWL) —This procedure uses shock waves to break up stones that are too large to pass. It requires anesthesia and may cause blood in the urine and minor back pain for a few days.
- Percutaneous nephrolithotomy—This procedure uses a scope placed through a small tube in the back to remove a kidney stone that is too big to pass.
- Lithotomy—Lithotomy is open surgery to remove a kidney stone. This procedure is rarely used now.
Prevention
Once you have formed a kidney stone, you are more likely to form another. Here are some steps to prevent more stones from forming:
- Drink plenty of fluids, especially water.
-
Don't change your diet without consulting your doctor. Recommendations will be based on the type of stones you've had, and the results of your 24-hour urine tests. Be sure to ask your doctor for a list of the foods you should avoid, or meet with a dietitian who can help you understand your dietary restrictions. You may be advised to do the following:
- Avoid apple and grapefruit juices.
- Increase intake of cranberry juice.
- Avoid foods high in oxalate, such as spinach.
- Eat less meat, fish, and poultry. These foods increase urine acidity.
- Decrease your sodium intake (especially if you have calcium stones).
- Increase your intake of magnesium.
- Drink lemonade daily.
- Increase your fiber intake.
- Avoid excess weight.
- If you have an enlarged parathyroid gland, you may need to have it removed surgically.
-
Medications may include:
- Drugs that control the amount of acid in the urine
- Allopurinol or sodium cellulose phosphate to treat urine high in calcium
- Hydrochlorothiazide (a diuretic) that alters calcium excretion in the urine
- Thiola to reduce the amount of cystine in the urine
RESOURCES:
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
http://www.niddk.nih.gov
National Kidney Foundation
http://www.kidney.org
UrologyHealth.org
http://www.urologyhealth.org
CANADIAN RESOURCES:
Canadian Health Network
http://www.canadian-health-network.ca/
The Kidney Foundation of Canada
http://www.kidney.ab.ca
References:
Borghi L, Meschi T, Maggiore U, Prati B. Dietary therapy in idiopathic nephrolithiasis. Nutr Rev. 2006;64:301-312.
Coe FL, Evan A, Worcester E. Kidney stone disease. J Clin Invest. 2005;115:2598-2608.
Guidelines from the American Urological Association. American Urological Association website. Available at: http://www.auafoundation.org/auafhome.asp .
Kang DE, Sur RL, Haleblian GE, Fitzsimons NJ, Borawski KM, and Preminger GM. Long-term lemonade based dietary manipulation in patients with hypocitraturic nephrolithiasis. J Urol. 2007;177:1358-1362.
Martini LA, Wood RJ. Should dietary calcium and protein be restricted in patients with nephrolithiasis? Nutr Rev. 2000;58:111-117.
National Institute of Diabetes and Digestive and Kidney Diseases website. Available at: http://www.niddk.nih.gov .
Pearle MS, Lingemann JE, Leveillee R, et al. Prospective, randomized controlled trial comparing shock wave lithotripsy and ureteroscopy for lower pole caliceal calculi 1 cm or less. J Urol. 2005;173:2005-2009.
Wein A, ed. Campbell-Walsh Urology. 9th ed. Philadelphia, PA: Saunders, Elsevier; 2007.
* 1 Updated section on Medications on 11/29/06 according to the following study, as cited by DynaMed's Systematic Literature Surveillance : Hollingsworth JM, Rogers MA, Kaufman SR, et al. Medical therapy to facilitate urinary stone passage: a meta-analysis. Lancet. 2006;368:1171-1179.
* 2 Updated section on Medications on 7/12/06 according to the following study, as cited by DynaMed's Systematic Literature Surveillance : Mora B, Giorni E, Dobrovits M, et al. Transcutaneous electrical nerve stimulation: an effective treatment for pain caused by renal colic in emergency care. J Urol. 2006;175:1737-1741; discussion 1741.
Last reviewed January 2008 by Adrienne Carmack, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
Copyright © 2007 EBSCO Publishing All rights reserved.
