The kidneys are the organs that remove waste products from the blood, maintain hydration levels, balance the body’s electrolytes and produce some vital hormones. Occasionally, some waste products will form crystals that can build up to form a stone. These stones can block areas inside the kidney or can block the tube that connects the kidney to the bladder, the ureter. A study of the U.S. population by the National Health and Nutrition Examination Surveys, published in 2003, showed that kidney stones are increasing in the United States.
Definition
Not all kidney stones are the same. The cause of kidney stones is an abnormal amount of minerals and waste products that can form crystals that develop into stones. The majority of stones are calcium and form as calcium oxalate, but other stones include struvite stones, made of magnesium and ammonia; uric stones, which form when the urine is too acidic; and the rare cystine stones. The appearance and color for each stone varies depending on its composition.
Diagnosis
The doctor will give you an exam and look at your medical history. Diagnosis can be confirmed by either computed tomography, ultrasonography, X-ray or intravenous pyelography. Computed tomography is the preferred method of diagnosis as it can detect stones as small as 1 to 2 mm. It does not require radioactivity and can identify other disorders that may be causing symptoms.
Causes
Some people have a genetic predisposition that can alter metabolism and lead to an increase in waste products that can form crystals. Certain conditions can increase the risk of developing kidney stones, such as hyperparathyroidism, with 10 percent to 20 percent of those with this condition expected to get stones. Other conditions that increase the risk of kidney stones include gout, high-blood pressure, obesity, diabetes and metabolic disorders. Medications such as water pills or diuretics, drugs containing calcium such as antacids, allopurinol and some antiretroviral drugs can increase the risk of kidney stones. Other causes include dehydration, infection and inflammatory bowel disease. Some stones are idiopathic, so the cause is never determined.
Treatment
Stones as large as 1 cm may be passed without the need for surgery. Nonsteroidal anti-inflammatory drugs are effective for pain relief while the stone is passing. Dr. John Hollingsworth, whose study was published in the the journal Lancet in 2006, reviewed nine random trials and showed that alpha-blockers and calcium channel blockers increased the stones' passage compared with those that had no treatment. A study published in the journal Endocrinology and Metabolism Clinics in North America suggests that up to 20 percent of symptomatic kidney stones will require medical intervention. Extra-corporeal shock wave lithotripsy uses sound waves to break up stones.
Prevention
Almost half of all patients will have a recurrence of their stones. Preventing recurrence is determined by the type of stone, as it requires altering the conditions that caused the formation of stones. Increasing fluid consumption alters the minerals in the urine, and urine volume is beneficial in preventing stone formation. Controlling other diseases and disorders may help. The doctor may recommend altering diet and may recommend medications.
Complications
Kidney stones can cause damage to the affected kidneys. If the stone blocks the urine from leaving the kidney, build-up of urine can cause irreversible damage to the kidney. Patients who have had kidney stones may be more susceptible to urinary tract infections.
References
- Kidney International (journal); "Time Trends in Reported Prevalence of Kidney Stones in the United States: 1976-1994"; K.K. Stamatelou, et al; May 2003
- New England Journal of Medicine; "A 10-year prospective study of primary hyperparathyroidism with or without parathyroid surgery"; S.J.Silverberg et al; October 1999
- Lancet (journal); "Medical Therapy to facilitate Urinary Stone Passage: A Meta-analysis"; J.M. Hollingsworth; September 2006
- Endocrinology and Metabolism Clinics in North America (journal); December 2002
