Questions and Answers about Stones
1. What is a kidney stone?
Kidney stones are typically firm objects that arise in the kidney due to an interaction of genetic and environmental factors in the majority of cases. Stones are formed when salts, minerals and other chemicals in the urine have a higher than normal concentration. The majority of kidney stones are composed of calcium, and a combination of oxalate or phosphate or both that crystallize and aggregate together, eventually developing a stone. This can be due to excessive excretion of these chemicals in urine and/or dehydration.
Some stones remain in the kidneys. They are typically small, less than 5 mm in size. However, some patients develop extremely large stones which may occupy the majority of urine space within a kidney. Small stones may pass from the kidney into the ureter (the tube draining urine from the kidney to the bladder). If the stone travels to the bladder, the majority of patients are able to pass the stone out of their body.
2. How is stone disease diagnosed?
One of the main symptoms is pain, including severe pain in the flank, abdomen or groin areas. Patients will frequently have nausea and vomiting during episodes of severe pain. Other symptoms include reddish urine and frequent urination. Some patients may have persistent problems with urinary tract infections.
A computed tomographic scan (CT scan) is the most sensitive technique for confirming this diagnosis in the acute setting. Other tests may be necessary for evaluating patients with kidney stones.
3. Do you “pass” the stones, have them “busted” or have surgery?
Most patients have small stones and pass them spontaneously. They are typically administered analgesics for pain management. They may also be given medications to facilitate stone passage. If they are not able to pass their stones, patients may be treated with shock wave lithotripsy or urteroscopic stone removal.
Shock wave lithotripsy is a non-invasive procedure where externally generated shock waves are usually pass out of the urinary tract. Ureteroscopy is a procedure where a scope is passed through the urethra into the bladder and then into the ureter or kidney. Instruments are then used to remove or fragment the stone.
Some patients with extremely large stones in their kidneys or ureter may need to undergo a procedure in which hollow tubes are placed through the patient’s back and into the kidney. A scope is directed through the tube providing visualization of the stone which is then fragmented and removed.
At Wake Forest Baptist, we have a new instrument called the Cyberwand that uses ultrasonic energy to efficiently fragment stone and remove it from the kidney. A minority of patients may need to undergo a laparoscopic procedure for stone removal. The abdomen is distended with carbon dioxide gas during this procedure and instruments are then used to remove the stone(s). Less than one percent of patients now require open surgery for stone removal. At Wake Forest Baptist, we have a comprehensive program where all of the aforementioned procedures are done
4. Will the kidney stones come back?
About half of patients develop another stone within 10 years. Certain dietary habits may reduce the risk of recurrent stone formation including consuming a lot of fluids and citrus fruit, having one dairy product serving with each meal, and limiting the intake of animal protein, sodium and oxalate.
Other medical conditions may be associated with kidney stone formation, including bowel disease, gout, diabetes mellitus, spinal cord injury, hypertension (high blood pressure), hyperparathyroidism and obesity. Patients can be evaluated with blood and urine tests to identify metabolic abnormalities that predispose them to kidney stone formation. These abnormalities can usually be improved or corrected with dietary modifications and the administration of certain medications.
At Wake Forest we have a comprehensive kidney stone prevention program where these tests are undertaken and patients are then assigned to dietary modifications or certain medications. We conduct research studies on the causes of kidney stone formation and prevention. We encourage our patients to participate in these studies as they may benefit from the results and perhaps help others afflicted with this problem.